Researcher Profile and Settings

Master

Affiliation (Master)

• Faculty of Information Science and Technology　Electronics for Informatics　Integrated Systems Engineering

Affiliation (Master)

• Faculty of Information Science and Technology　Electronics for Informatics　Integrated Systems Engineering

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Profile and Settings

Profile and Settings

• Name (Japanese)

  Murayama

• Name (Kana)

  Akihiro

• Name

  200901040396602318

Alternate Names

https://www.ist.hokudai.ac.jp/
https://www.ist.hokudai.ac.jp/eng/

Achievement

Research Interests

• Optically functional nanomaterial   Spin-functional optical/photonic device   Quantum-dot-based optical/photonic device   Pico-second time-resolved photoluminescence scpectroscopy   Semiconductor nanostructure   Ultrafast spin dynamics   Semiconductor quantum dot   

Research Areas

• Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Electric/electronic material engineering / Semiconductor quantum dot, Optical device, Spin-functional optical device
• Nanotechnology/Materials / Optical engineering and photonics / Time-resolved photoluminescence spectroscopy, Spin dynamics
• Nanotechnology/Materials / Nanostructure physics / Semiconductor quantum dot, Optical device, Spin-functional optical device
• Nanotechnology/Materials / Crystal engineering / Semiconductor quantum dot

Research Experience

• 2023/10 - Today Hokkaido University
• 2023/06 - Today Hokkaido University
• 2008/10 - Today Hokkaido University Faculty of Information Science and Technology professor
• 2017 - 2020 Advisor to the President for Research Strategy
• 2016 - 2018 Hokkaido University Graduate School of Information Science and Technology Vice-Dean for Research
• 2001/02 - 2008/09 Tohoku University Institute of Multidisciplinary Research for Advanced Materials Associate Professor
• 2007 - 2008 Tokyo Institute of Technology
• 2003 - 2005 New Energy and Industrial Technology Development Organization Project “Focus21” Project Reader, Advanced Nano Glass for Devices
• 2001 - 2005 National Institute of Advanced Industrial Science and Technology
• 1985/04 - 2001/01 Asahi Glass Co. Ltd. Research and Development
• 1996 - 1999 University of Arizona Optical Sciences Center

Education

• 1994/04 - 1995/03  Tohoku University  Graduate School of Engineering  Department of Applied Physics
• 1983/04 - 1985/03  Tohoku University  Graduate School of Engineering  Department of Applied Physics
• 1979/04 - 1983/03  Tohoku University  Faculty of Engineering  Department of Applied Physics

Committee Memberships

• 2010 -2012   The Japan Society of Applied Physics   Editorial board member
• 2008 -2009   The Physical Society of Japan   Member of program committee
• 2004 -2008   The New Glass Forum   Respective special member
• 2004 -2008   The Japan Society of Applied Physics   Member of representative committee

Published Papers

• High-temperature efficient luminescence of dilute-nitride InGaAsN quantum dots with deep electron potential

  Ayano Morita, Satoshi Hiura, Junichi Takayama, Akihiro Murayama

  Journal of Applied Physics 134 (22) 0021-8979 2023/12/11 [Refereed]
   

  The temperature dependence of the optical properties of In0.4Ga0.6As0.98N0.02 quantum dots (QDs) was investigated using continuous-wave and time-resolved photoluminescence (PL). Significant increases in the PL peak energy and the PL linewidth were observed at temperatures above 200 K, which reflected the high luminescence efficiency of ground and excited states at high temperatures. The PL decay times of the ground state were almost constant between 200 and 300 K at 200–220 ps, which were significantly longer than that of 38 ps for the In0.4Ga0.6As QDs at 300 K. The temperature independence of the PL decay time represents significant suppression of the thermal escape and the thermal excitation of electrons because the electron ground-state localization energy is much larger than the thermal energy. The PL intensity of the In0.4Ga0.6As0.98N0.02 QDs was seven times stronger than that of the In0.4Ga0.6As QDs at 300 K, and this tendency was maintained up to 400 K with a PL intensity one order of magnitude stronger. These findings demonstrate that lowering the QD conduction band by nitrogen incorporation is an effective approach for achieving strong QD luminescence above room temperature.
• Effect of dilute nitride GaNAs quantum well thickness on spin amplification dynamics of tunnel-coupled InAs quantum dots

  Shino Sato, Satoshi Hiura, Junichi Takayama, Akihiro Murayama

  Applied Physics Letters 123 (23) 0003-6951 2023/12/04 [Refereed]
   

  Electron spin dynamics of dilute nitride GaNAs quantum well (QW)-InAs quantum dots (QDs) tunnel-coupled structures having different QW thicknesses were studied via circularly polarized time-resolved photoluminescence. The rate equation fitting considering a capture of QD electron spins by the GaNAs localized states via tunnel transfer revealed that the spin amplification dynamics of the QDs depended on the QW thickness. For the QW thickness of 5 nm, although the temporal amplification of QD electron spin polarization was slow owing to the weak wavefunction coupling between the QW and QD, the long duration of high electron spin polarization was observed because of the suppressed capture of QD majority spins relative to the efficient removal of QD minority spins. When the QW thickness increased from 5 to 20 nm, the strong spin filtering in GaNAs and strong wavefunction coupling led to the fast amplification of QD electron spin polarization with high initial spin polarization. However, the spin polarization rapidly decays after the amplification owing to the removal of both QD majority and minority spins, originating from many effective localized states. These results indicate that the time-dependent QD electron spin polarization and the resultant spin amplification can be widely tuned by changing the thickness of the tunnel-coupled GaNAs QW.
• Vapor‐Induced Assembly of a Platinum(II) Complex Loaded on Layered Double Hydroxide Nanoparticles

  Tamami Morimoto, Masaki Yoshida, Ayana Sato‐Tomita, Shunsuke Nozawa, Junichi Takayama, Satoshi Hiura, Akihiro Murayama, Atsushi Kobayashi, Masako Kato

  Chemistry – A European Journal 29 (60) 0947-6539 2023/09/29 [Refereed]
   

  Abstract Controlled self‐assembly of Pt^II complexes is key to the development of optical and stimuli‐responsive materials, but designing and precisely controlling them is still difficult owing to weak intermolecular interactions. Herein, we report the successful water‐vapor‐induced assembly of an anionic Pt^II complex [Pt(CN)₂(ppy)]⁻ (Hppy=2‐phenylpyridine) electrostatically loaded onto cationically charged layered double hydroxide (LDH) nanoparticles consisting of Mg²⁺ and Al³⁺ ions. When the Pt^II complexes were densely loaded onto the LDH nanoparticles, the assembly was maintained, even in dilute aqueous media. In the case of sparse loading, the Pt^II complexes were loaded discretely in the dry state; however, when water vapor was adsorbed, the increased mobility of the Pt^II complexes led to their assembly on the LDH nanoparticles. The presence of water vapor led to a drastic change in luminescence from green to orange.
• GaAs/GaInNAs core-multishell nanowires with a triple quantum-well structure emitting in the telecommunication range

  Kaito Nakama, Mitsuki Yukimune, Naohiko Kawasaki, Akio Higo, Satoshi Hiura, Akihiro Murayama, Mattias Jansson, Weimin M. Chen, Irina A. Buyanova, Fumitaro Ishikawa

  Applied Physics Letters 123 (8) 0003-6951 2023/08/21 [Refereed]
   

  Semiconducting nanowires (NWs) fabricated from III–V materials have gained significant attention for their application in advanced optoelectronic devices. Here, the growth of GaAs/GaInNAs/GaAs core-multishell NWs with a triple quantum-well structure, having about 2% N and 20% In, is reported. The NWs are grown via selective area plasma-assisted molecular beam epitaxy on patterned Si(111) substrates with SiO2 mask holes. The nucleation and growth of the GaAs nanowires' core are carried out by Ga-induced vapor–liquid–solid growth at the open holes. Finely controlled, vertically aligned, regular core-multishell NWs with uniform wire length and diameter are obtained with a 96% yield and targeted nitrogen concentrations of 0%, 2%, and 3%. The GaInNAs NWs exhibit a spectral red shift relative to the GaAs NWs' peak. Their emission wavelength increases with the N content reaching up to 1.26 μm, which makes them a promising tool in telecommunication light sources.
• Electric-field driven source of photocarriers for tunable electron spin polarization in InGaAs quantum dots

  Hiroto Kise, Satoshi Hiura, Soyoung Park, Junichi Takayama, Kazuhisa Sueoka, Akihiro Murayama

  Applied Physics Letters 122 (23) 0003-6951 2023/06/05 [Refereed]
   

  Electric-field control of spin polarization of electrons during injection into InGaAs quantum dots (QDs) was studied via circularly polarized time-resolved photoluminescence. Electric-field modulation of optical spin polarization in QDs will play a key role in future progress of semiconductor opto-spintronics. The tuning of band potentials by applying external electric fields can not only affect spin-injection efficiencies but also switch dominant spin-injection layers. In this study, we developed a QD-based electric-field-effect optical spin device with two different spin-injection layers, which consisted of a GaAs and GaAs/Al0.15Ga0.85As superlattice (SL) barriers. The bias-voltage modulation of the optical spin polarization in QDs was demonstrated by changing the spin polarization degree of electrons injected from these barriers into the QD via the electric-field switching of the spin-injection layers. This was achieved by exploiting the difference in spin relaxation properties between bulk GaAs and the SL. This proposed structure, which comprised of one luminescent layer and two spin-injection layers, is highly scalable because the modulation range of optical spin polarization can be enhanced by changing the combination of spin-injection layers, as well as the material used and its layer thickness.
• Efficient Room-Temperature Operation of a Quantum Dot Spin-Polarized Light-Emitting Diode under High-Bias Conditions

  Kohei Etou, Satoshi Hiura, Soyoung Park, Junichi Takayama, Agus Subagyo, Kazuhisa Sueoka, Akihiro Murayama

  Physical Review Applied 19 (2) 2023/02/21 [Refereed]
  
• Room-temperature electric field control of spin filtering efficiency for enhanced modulation of optical spin polarization in a defect-functional 0D–2D hybrid nanostructure

  Soyoung Park, Satoshi Hiura, Hiroto Kise, Junichi Takayama, Kazuhisa Sueoka, Akihiro Murayama

  Nanoscale 15 (41) 16784 - 16794 2040-3364 2023 [Refereed]
   

  We demonstrate an electric field control of optical spin polarization of InAs quantum dots in the range of 15–40% at room temperature. This accomplishment is achieved by tuning the spin amplification degree of dilute nitride GaNAs quantum well.
• Wafer-scale integration of GaAs/AlGaAs core–shell nanowires on silicon by the single process of self-catalyzed molecular beam epitaxy

  Keisuke Minehisa, Ryo Murakami, Hidetoshi Hashimoto, Kaito Nakama, Kenta Sakaguchi, Rikuo Tsutsumi, Takeru Tanigawa, Mitsuki Yukimune, Kazuki Nagashima, Takeshi Yanagida, Shino Sato, Satoshi Hiura, Akihiro Murayama, Fumitaro Ishikawa

  Nanoscale Advances 5 (6) 1651 - 1663 2023 [Refereed]
   

  Optically efficient GaAs/AlGaAs core–shell nanowires on 2-inch Si wafers before (front right) and after (others) growth. The samples show a dark-colored feature indicating light absorption on the substrate surface.
• Efficient Room‐Temperature Voltage Control of Picosecond Optical Spin Orientation Using a III‐V Semiconductor Nanostructure

  Soyoung Park, Satoshi Hiura, Junichi Takayama, Kazuhisa Sueoka, Akihiro Murayama

  Advanced Electronic Materials 2200588 - 2200588 2199-160X 2022/08/15 [Refereed][Not invited]
  
• Optical characterization and emission enhancement property of Ag nanomesh structure fabricated by nanosphere lithography

  Mai Ugajin, Soyoung Park, Takayuki Kiba, Junichi Takayama, Satoshi Hiura, Akihiro Murayama, Midori Kawamura, Yoshio Abe

  Surface and Coatings Technology 435 128258 - 128258 0257-8972 2022/04 [Refereed][Not invited]
  
• Thermo‐ and Mechano‐Triggered Luminescence ON/OFF Switching by Supercooled Liquid/Crystal Transition of Platinum(II) Complex Thin Films

  Masaki Yoshida, Verner Sääsk, Daisuke Saito, Nobutaka Yoshimura, Junichi Takayama, Satoshi Hiura, Akihiro Murayama, Kaija Põhako‐Esko, Atsushi Kobayashi, Masako Kato

  Advanced Optical Materials 10 (7) 2102614 - 2102614 2195-1071 2022/04 [Refereed][Not invited]
  
• Room-temperature spin transport properties in In0.5Ga0.5As quantum dot spin-polarized light-emitting diode

  Kohei Etou, Satoshi Hiura, Soyoung Park, Kazuya Sakamoto, Junichi Takayama, Agus Subagyo, Kazuhisa Sueoka, Akihiro Murayama

  Physical Review Applied 16 014034-1 - 014034-10 2021/07 [Refereed]
  
• Room-temperature electron spin polarization exceeding 90% in an opto-spintronic semiconductor nanostructure via remote spin filtering

  Yuqing Huang, Ville Polojärvi, Satoshi Hiura, Pontus Höjer, Arto Aho, Riku Isoaho, Teemu Hakkarainen, Mircea Guina, Shino Sato, Junichi Takayama, Akihiro Murayama, Irina A. Buyanova, Weimin M. Chen

  Nature Photonics 15 475 - 482 2021/04 [Refereed]
  
• Electric-Field-Effect Spin Switching with an Enhanced Number of Highly Polarized Electron and Photon Spins Using p‑Doped Semiconductor Quantum Dots

  Soyoung Park, Hang Chen, Satoshi Hiura, Junichi Takayama, Kazuhisa Sueoka, Akihiro Murayama

  ACS Omega 6 8561 - 8569 2021/03 [Refereed]
  
• Intense Red‐Blue Luminescence Based on Superfine Control of Metal–Metal Interactions for Self‐Assembled Platinum(II) Complexes

  Daisuke Saito, Tomohiro Ogawa, Masaki Yoshida, Junichi Takayama, Satoshi Hiura, Akihiro Murayama, Atsushi Kobayashi, Masako Kato

  Angewandte Chemie International Edition 59 (42) 18723 - 18730 1433-7851 2020/10/12 [Refereed][Not invited]
  
• Highly Efficient Room-Temperature Electron-Photon Spin Conversion Using a Semiconductor Hybrid Nanosystem with Gradual Quantum Dimensionality Reduction

  Satoshi Hiura, Mizuki Takishita, Junichi Takayama, Shino Sato, Akihiro Murayama

  Physical Review Applied 14 (4) 2020/10/08 [Refereed][Not invited]
  
• Asymmetric spin relaxation induced by residual electron spin in semiconductor quantum-dot-superlattice hybrid nanosystem

  Satoshi Hiura, Saeko Hatakeyama, Junichi Takayama, Akihiro Murayama

  Applied Physics Letters 116 (26) 262407 - 262407 0003-6951 2020/06/29 [Refereed][Not invited]
  
• Suppression of thermally excited electron-spin relaxation in InGaAs quantum dots using p-doped capping layers toward enhanced room-temperature spin polarization

  Shino Sato, Satoshi Hiura, Junichi Takayama, Akihiro Murayama

  Applied Physics Letters 116 (18) 182401 - 182401 0003-6951 2020/05/04 [Refereed][Not invited]
  
• Size dependence of emission enhancement of Tris(8-hydroxyquinolinato) aluminum with plasmonic Al nanostructure

  Natsumi Iijima, Mai Ugajin, Takayuki Kiba, Midori Kawamura, Yoshio Abe, Kyung Ho Kim, Akio Higo, Junichi Takayama, Satoshi Hiura, Akihiro Murayama

  Thin Solid Films 700 137920 - 137920 0040-6090 2020/04 [Refereed][Not invited]
  
• Temperature dependence of inter-dot electron-spin transfer among laterally coupled excited states in high-density InGaAs quantum dots

  Shino Sato, Satoshi Hiura, Junichi Takayama, Akihiro Murayama

  Journal of Applied Physics 127 (4) 043904 - 043904 0021-8979 2020/01/31 [Refereed][Not invited]
  
• Enhanced hetero-dimensional electron-spin injection in a resonantly tunnel-coupled InGaAs quantum dot–well nanosystem

  Hang Chen, Satoshi Hiura, Junichi Takayama, Soyoung Park, Kazuhisa Sueoka, Akihiro Murayama

  Applied Physics Express 13 (1) 015003 - 015003 1882-0778 2020/01/01 [Refereed][Not invited]
  
• New Optical Functionalities Developed by Using Semiconductor Quantum-dot Crystals

  Akihiro MURAYAMA

  電子情報通信学会誌 102 (10) 938 - 941 2019/10 [Refereed][Invited]
  
• Photoluminescence of InGaAs/GaAs Quantum Nanodisk in Pillar Fabricated by Biotemplate, Dry Etching, and MOVPE Regrowth

  Akio Higo, Takayuki Kiba, Junichi Takayama, Chang Yong Lee, Cedric Thomas, Takuya Ozaki, Hassanet Sodabanlu, Masakazu Sugiyama, Yoshiaki Nakano, Ichiro Yamashita, Akihiro Murayama, Seiji Samukawa

  ACS Applied Electronic Materials 1 (9) 1945 - 1951 2637-6113 2019/09/24 [Refereed][Not invited]
  
• Layer-selective spin amplification in size-modulated quantum nanocolumn

  Satoshi Hiura, Shotaro Saito, Junichi Takayama, Takayuki Kiba, Akihiro Murayama

  Applied Physics Letters 115 (1) 013102 - 013102 0003-6951 2019/07 [Refereed][Not invited]
  
• Emission enhancement of tris(8-quinolinolato)aluminum with Al nanotriangle arrays fabricated by nanosphere lithography

  Takayuki Kiba, Natsumi Iijima, Kazuki Yanome, Midori Kawamura, Yoshio Abe, Kyung Ho Kim, Mai Takase, Akio Higo, Junichi Takayama, Satoshi Hiura, Akihiro Murayama

  Applied Surface Science 478 49 - 53 0169-4332 2019/06 [Refereed][Not invited]
  
• Electron-transfer-induced metallic electronic states in a H/Fe3O4(001) film subsurface

  Satoshi Hiura, Agus Subagyo, Akihiro Murayama, Kazuhisa Sueoka

  Applied Physics Express 12 (5) 055502 - 055502 1882-0778 2019/05/01 [Refereed][Not invited]
  
• Electric field control of spin polarity in spin injection into InGaAs quantum dots from a tunnel-coupled quantum well

  Hang Chen, Satoshi Hiura, Junichi Takayama, Soyoung Park, Kazuhisa Sueoka, Akihiro Murayama

  Applied Physics Letters 114 (13) 133101 - 133101 0003-6951 2019/04 [Refereed][Not invited]
  
• Quantum spin transport to semiconductor quantum dots through superlattice

  Satoshi Hiura, Kodai Itabashi, Kazuki Takeishi, Junichi Takayama, Takayuki Kiba, Akihiro Murayama

  Applied Physics Letters 114 (7) 072406 - 072406 0003-6951 2019/02/18 [Refereed][Not invited]
  
• Interdot carrier and spin dynamics in a two-dimensional high-density quantum-dot array of InGaAs with quantum dots embedded as local potential minima

  Satoshi Hiura, Masayuki Urabe, Kazuki Takeishi, Kodai Itabashi, Junichi Takayama, Takayuki Kiba, Kazuhisa Sueoka, Akihiro Murayama

  Semiconductor Science and Technology 34 (2) 025001 - 025001 0268-1242 2019/02/01 [Refereed][Not invited]
  
• Temperature dependence of the radiative recombination time in laterally coupled GaAs quantum dots

  Heedae Kim, Akihiro Murayama, Jongsu Kim, Jindong Song

  Applied Surface Science 457 497 - 500 0169-4332 2018/11 [Refereed][Not invited]
  
• Persistent High Polarization of Excited Spin Ensembles During Light Emission in Semiconductor Quantum-Dot-Well Hybrid Nanosystems

  Kazuki Takeishi, Satoshi Hiura, Junichi Takayama, Kodai Itabashi, Masayuki Urabe, Akihiro Washida, Takayuki Kiba, Akihiro Murayama

  Physical Review Applied 10 (3) 2018/09/10 [Refereed][Not invited]
  
• Carrier Relaxation Dynamics Between Localized Vertical Confinement States in GaAs/AlGaAs Quantum Rings

  Seongho Park, Jongsu Kim, Junich Takayama, Akihiro Murayama, Kwangseuk Kyhm

  Journal of the Korean Physical Society 73 (3) 314 - 319 0374-4884 2018/08 [Refereed][Not invited]
  
• Photoluminescence enhancement of tris(8-hydroxyquinolinato)aluminum thin film by plasmonic Ag nanotriangle array fabricated by nanosphere lithography

  Kazuki Yanome, Takayuki Kiba, Kazuaki Masui, Midori Kawamura, Yoshio Abe, Kyung Ho Kim, Mai Takase, Junichi Takayama, Akihiro Murayama

  Thin Solid Films 660 907 - 912 0040-6090 2018/08 [Refereed][Not invited]
  
• Time-resolved photoluminescence study of tris(8-hydroxyquinolinato) aluminium with surface plasmon resonance of Ag nanoparticles

  Kazuaki Masui, Takayuki Kiba, Aoto Sato, Kazuki Yanome, Midori Kawamura, Yoshio Abe, Kyung Ho Kim, Hee Dae Kim, Junichi Takayama, Akihiro Murayama

  Thin Solid Films 660 938 - 943 0040-6090 2018/08 [Refereed][Not invited]
  
• Interdot spin transfer dynamics in laterally coupled excited spin ensemble of high-density InGaAs quantum dots

  Satoshi Hiura, Kazuki Takeishi, Masayuki Urabe, Kodai Itabashi, Junichi Takayama, Takayuki Kiba, Kazuhisa Sueoka, Akihiro Murayama

  Applied Physics Letters 113 (2) 023104 - 023104 0003-6951 2018/07/09 [Refereed][Not invited]
  
• Magnetic field insensitive photoluminescence decay of ZnSe/CdS core/shell type-II colloidal quantum dots

  Woojin Lee, Seongho Park, Akihiro Murayama, Jong-soo Lee, Kwangseuk Kyhm

  Japanese Journal of Applied Physics 57 (6S1) 06HE06 - 06HE06 0021-4922 2018/06/01 [Refereed][Not invited]
  
• Temperature-dependent radiative and non-radiative dynamics of photo-excited carriers in extremely high-density and small InGaN nanodisks fabricated by neutral-beam etching using bio-nano-templates

  Yafeng Chen, Takayuki Kiba, Junichi Takayama, Akio Higo, Tomoyuki Tanikawa, Shula Chen, Seiji Samukawa, Akihiro Murayama

  Journal of Applied Physics 123 (20) 204305 - 204305 0021-8979 2018/05/28 [Refereed][Not invited]
  
• Growth of Semiconductor Self-assembled Quantum Dots by Molecular Beam Epitaxy and the Dynamics of Photo-excited Carriers

  Akihiro MURAYAMA, Junichi TAKAYAMA, Satoshi HIURA, Takayuki KIBA

  Vacuum and Surface Science 61 (5) 315 - 324 2433-5835 2018/05/10 [Refereed][Invited]
  
• Effect of a Phonon Bottleneck on Exciton and Spin Generation in Self-Assembled In1−xGaxAs Quantum Dots

  Y. Q. Huang, I. A. Buyanova, X. J. Yang, A. Murayama, W. M. Chen

  Physical Review Applied 9 (4) 2018/04/26 [Refereed][Not invited]
  
• Optical Study of Sub-10 nm In0.3Ga0.7N Quantum Nanodisks in GaN Nanopillars

  Akio Higo, Takayuki Kiba, Shula Chen, Yafeng Chen, Tomoyuki Tanikawa, Cedric Thomas, Chang Yong Lee, Yi-Chun Lai, Takuya Ozaki, Junichi Takayama, Ichiro Yamashita, Akihiro Murayama, Seiji Samukawa

  ACS Photonics 4 (7) 1851 - 1857 2330-4022 2017/07/19 [Refereed][Not invited]
  
• Spectroscopic and Photoluminescent Properties of Indium Zinc Oxide (IZO) and IZO/Ag/IZO Sandwiched Film

  Kazuki Yanome, Takayuki Kiba, Midori Kawamura, Yoshio Abe, Kyung Ho Kim, Junichi Takayama, Akihiro Murayama

  Journal of Electronic Materials 46 (7) 3873 - 3879 0361-5235 2017/07 [Refereed][Not invited]
  
• Direct observation of subsurface charge ordering in Fe3O4(001) by scanning tunneling microscopy/spectroscopy

  Satoshi Hiura, Akira Ikeuchi, Masafumi Jochi, Riku Yamazaki, Sotaro Takahashi, Agus Subagyo, Akihiro Murayama, Kazuhisa Sueoka

  Applied Physics Express 10 (4) 045701 - 045701 1882-0778 2017/04/01 [Refereed][Not invited]
  
• Emission enhancement in indium zinc oxide(IZO)/Ag/IZO sandwiched structure due to surface plasmon resonance of thin Ag film

  Takayuki Kiba, Kazuki Yanome, Midori Kawamura, Yoshio Abe, Kyung Ho Kim, Junichi Takayama, Akihiro Murayama

  Applied Surface Science 389 906 - 910 0169-4332 2016/12 [Refereed][Not invited]
  
• Nanometer scale fabrication and optical response of InGaN/GaN quantum disks

  Yi-Chun Lai, Akio Higo, Takayuki Kiba, Cedric Thomas, Shula Chen, Chang Yong Lee, Tomoyuki Tanikawa, Shigeyuki Kuboya, Ryuji Katayama, Kanako Shojiki, Junichi Takayama, Ichiro Yamashita, Akihiro Murayama, Gou-Chung Chi, Peichen Yu, Seiji Samukawa

  Nanotechnology 27 (42) 425401 - 425401 0957-4484 2016/10/21 [Refereed][Not invited]
  
• Temperature-Dependent Operation of GaAs Quantum Nanodisk LEDs with Asymmetric AlGaAs Barriers

  Yosuke Tamura, Akio Higo, Takayuki Kiba, Cedric Thomas, Junichi Takayama, Ichiro Yamashita, Akihiro Murayama, Seiji Samukawa

  IEEE Transactions on Nanotechnology 15 (3) 557 - 562 1536-125X 2016/05 [Refereed][Not invited]
  
• Power-dependent spin amplification in (In, Ga)As/GaAs quantum well via Pauli blocking by tunnel-coupled quantum dot ensembles

  S. L. Chen, T. Kiba, X. J. Yang, J. Takayama, A. Murayama

  Applied Physics Letters 108 (15) 152103 - 152103 0003-6951 2016/04/11 [Refereed][Not invited]
  
• Temperature-dependent spin injection dynamics in InGaAs/GaAs quantum well-dot tunnel-coupled nanostructures

  S. L. Chen, T. Kiba, X. J. Yang, J. Takayama, A. Murayama

  Journal of Applied Physics 119 (11) 115701 - 115701 0021-8979 2016/03/21 [Refereed][Not invited]
  
• Tuning of the electrongfactor in defect-free GaAs nanodisks

  Li-Wei Yang, Yi-Chia Tsai, Yiming Li, Aiko Higo, Akihiro Murayama, S. Samukawa, O. Voskoboynikov

  Physical Review B 92 (24) 1098-0121 2015/12/15 [Refereed][Not invited]
  
• Electron g-factor and spin decoherence in GaAs quantum nanodisks fabricated by fully top-down lithography

  Toru Tanaka, Takayuki Kiba, Akio Higo, Cedric Thomas, Yosuke Tamura, Seiji Samukawa, Akihiro Murayama

  Journal of Crystal Growth 425 295 - 298 0022-0248 2015/09 [Refereed][Not invited]
  
• Time-resolved measurements of Cooper-pair radiative recombination in InAs quantum dots

  S. S. Mou

  Journal of Applied Physics 118 (7) 073102 - 073102 0021-8979 2015/08/21 [Refereed][Not invited]
  
• Light-Emitting Devices Based on Top-down Fabricated GaAs Quantum Nanodisks

  Akio Higo, Takayuki Kiba, Yosuke Tamura, Cedric Thomas, Junichi Takayama, Yunpeng Wang, Hassanet Sodabanlu, Masakazu Sugiyama, Yoshiaki Nakano, Ichiro Yamashita, Akihiro Murayama, Seiji Samukawa

  Scientific Reports 5 (1) 2015/08 [Refereed][Not invited]
  
• Optical observation of superconducting density of states in luminescence spectra of InAs quantum dots

  S. S. Mou, H. Irie, Y. Asano, K. Akahane, H. Nakajima, H. Kumano, M. Sasaki, A. Murayama, I. Suemune

  Physical Review B 92 (3) 1098-0121 2015/07/27 [Refereed][Not invited]
  
• Polarization anisotropy of exciton in self-assembled elliptical InP/InGaP quantum dots

  Inhong Kim, Takayuki Kiba, Akihiro Murayama, Jin Dong Song, Kwangseuk Kyhm

  Current Applied Physics 15 (6) 733 - 738 1567-1739 2015/06 [Refereed][Not invited]
  
• Size dependence of electron spin dephasing in InGaAs quantum dots

  Y. Q. Huang, Y. Puttisong, I. A. Buyanova, X. J. Yang, A. Subagyo, K. Sueoka, A. Murayama, W. M. Chen

  Applied Physics Letters 106 (9) 093109 - 093109 0003-6951 2015/03/02 [Refereed][Not invited]
  
• Impact of artificial lateral quantum confinement on exciton-spin relaxation in a two-dimensional GaAs electronic system

  Takayuki Kiba, Toru Tanaka, Yosuke Tamura, Akio Higo, Cedric Thomas, Seiji Samukawa, Akihiro Murayama

  AIP Advances 4 (10) 107112 - 107112 2014/10 [Refereed][Not invited]
  
• Anomalous spectral dependence of optical polarization and its impact on spin detection in InGaAs/GaAs quantum dots

  Y. Puttisong, Y. Q. Huang, I. A. Buyanova, X. J. Yang, A. Subagyo, K. Sueoka, A. Murayama, W. M. Chen

  Applied Physics Letters 105 (13) 132106 - 132106 0003-6951 2014/09/29 [Refereed][Not invited]
  
• Growth-temperature dependence of optical spin-injection dynamics in self-assembled InGaAs quantum dots

  Takafumi Yamamura, Takayuki Kiba, Xiaojie Yang, Junichi Takayama, Agus Subagyo, Kazuhisa Sueoka, Akihiro Murayama

  Journal of Applied Physics 116 (9) 094309 - 094309 0021-8979 2014/09/07 [Refereed][Not invited]
  
• Temperature dependence of the radiative recombination time in ZnO nanorods under an external magnetic field of 6T

  W. Lee, T. Kiba, A. Murayama, C. Sartel, V. Sallet, I. Kim, R. A. Taylor, Y. D. Jho, K. Kyhm

  Optics Express 22 (15) 17959 - 17959 2014/07/28 [Refereed][Not invited]
  
• Photophysical Properties and Biocompatibility of Photoluminescent Y2O3:Eu Nanoparticles in Polymethylmetacrylate Matrix

  Shigeaki Abe, Yusuke Hamba, Nobuki Iwadera, Shuichi Yamagata, Yasutaka Yawaka, Motohiro Uo, Junichiro Iida, Takayuki Kiba, Akihiro Murayama, Fumio Watari

  Journal of Nanoscience and Nanotechnology 14 (4) 2891 - 2894 1533-4880 2014/04/01 [Refereed][Not invited]
  
• Ultrafast spin tunneling and injection in coupled nanostructures of InGaAs quantum dots and quantum well

  Xiao-Jie Yang, Takayuki Kiba, Takafumi Yamamura, Junichi Takayama, Agus Subagyo, Kazuhisa Sueoka, Akihiro Murayama

  Applied Physics Letters 104 (1) 012406 - 012406 0003-6951 2014/01/06 [Refereed][Not invited]
  
• Preparation and biocompatibilities of luminescent europium-doped yttria and titania nanoparticles

  Shigeaki ABE, Yusuke HAMBA, Atsushi HYONO, Shuichi YAMAGATA, Motohiro UO, Junichiro IIDA, Takayuki KIBA, Akihiro MURAYAMA, Tsukasa AKASAKA, Fumio WATARI

  Journal of the Ceramic Society of Japan 122 (1423) 216 - 221 1882-0743 2014 [Refereed][Not invited]
  
• Temperature dependence of time-resolved photoluminescence in closely packed alignment of Si nanodisks with SiC barriers

  Takayuki Kiba, Yoshiya Mizushima, Makoto Igarashi, Chi-Hsien Huang, Seiji Samukawa, Akihiro Murayama

  Nanoscale Research Letters 8 (1) 2013/12 [Refereed][Not invited]
  
• Surface/interface-related optical properties in Si nanodisks fabricated by neutral-beam etching using bio-templates

  Takayuki Kiba, Kenta Suzaki, Hao Li, Makoto Igarashi, Seiji Samukawa, Akihiro Murayama

  Journal of Crystal Growth 378 493 - 496 0022-0248 2013/09 [Refereed][Not invited]
  
• Dynamics of electron-spin injection in a heterovalent GaAs/AlGaAs/ZnMnSe structure with a coupled double quantum well of GaAs/AlGaAs

  Y. Kuno, T. Sasaki, T. Kiba, V.Kh. Kaibyshev, F. Liaci, A.A. Toropov, S.V. Ivanov, A. Murayama

  Journal of Crystal Growth 378 393 - 396 0022-0248 2013/09 [Refereed][Not invited]
  
• Temperature dependence of the dynamics of optical spin injection in self-assembled InGaAs quantum dots

  Takayuki Kiba, Xiao-jie Yang, Takafumi Yamamura, Yuki Kuno, Agus Subagyo, Kazuhisa Sueoka, Akihiro Murayama

  Applied Physics Letters 103 (8) 082405 - 082405 0003-6951 2013/08/19 [Refereed][Not invited]
  
• Quantum size effects in GaAs nanodisks fabricated using a combination of the bio-template technique and neutral beam etching

  Yosuke Tamura, Toshiyuki Kaizu, Takayuki Kiba, Makoto Igarashi, Rikako Tsukamoto, Akio Higo, Weiguo Hu, Cedric Thomas, Mohd Erman Fauzi, Takuya Hoshii, Ichiro Yamashita, Yoshitaka Okada, Akihiro Murayama, Seiji Samukawa

  Nanotechnology 24 (28) 285301 - 285301 0957-4484 2013/07/19 [Refereed][Not invited]
  
• Photophysical Properties of Self-assembled Cyanine-dye Dimmer Formation Assisted by Cyclodextrin Inclusion Complexation

  Shigeaki Abe, Takashi Hirota, Takayuki Kiba, Naoyuki Miyakawa, Fumio Watari, Akihiro Murayama, Shin-Ichiro Sato

  Molecular Crystals and Liquid Crystals 579 (1) 22 - 29 1542-1406 2013/01 [Refereed][Not invited]
  
• Structure and Intermolecular Dynamics of Carbon Disulfide/Alcohols Binary Solution

  Takayuki Kiba, Takashi Hirota, Akihiro Murayama, Shin-Ichiro Sato

  Molecular Crystals and Liquid Crystals 579 (1) 103 - 109 1542-1406 2013/01 [Refereed][Not invited]
  
• High-density optical spin injection in self-assembled semiconductor quantum dots

  Akihiro Murayama, Norihiro Tamura, Tatsushiro Yamazaki, Takayuki Kiba

  Journal of Luminescence 133 110 - 113 0022-2313 2013/01 [Refereed][Not invited]
  
• Spectral Narrowing of UV-Visible Absorption and Emission Spectra of Anthracene-Derivatives in β-Cyclodextrin Nanocavity: Effects of Host/Guest Stoichiometry

  Shin-Ichiro Sato, Yuuki Yoshizumi, Takayuki Kiba, Akihiro Murayama, Shigeaki Abe

  Molecular Crystals and Liquid Crystals 568 (1) 60 - 65 1542-1406 2012/12/03 [Refereed][Not invited]
  
• Picosecond carrier dynamics induced by coupling of wavefunctions in a Si-nanodisk array fabricated by neutral beam etching using bio-nano-templates

  Takayuki Kiba, Yoshiya Mizushima, Makoto Igarashi, Seiji Samukawa, Akihiro Murayama

  Nanoscale Research Letters 7 (1) 2012/12 [Refereed][Not invited]
  
• Antiferromagnetic interaction in coupled CdSe/ZnMnSe quantum dot structures

  D. Dagnelund, Q. J. Ren, I. A. Buyanova, A. Murayama, W. M. Chen

  Applied Physics Letters 101 (5) 052405 - 052405 0003-6951 2012/07/30 [Refereed][Not invited]
  
• Sub-Picosecond Spin Relaxation of Bright Excitons and Imbalance Suppression in Asymmetric Cdse/Zns Nanocrystal Quantum Dots Under an Applied Magnetic Field

  Kwangseuk Kyhm, Jihoon Kim, Ho-Soon Yang, Koo-Chul Je, Akihiro Murayama

  Journal of Nanoscience and Nanotechnology 12 (3) 2919 - 2923 1533-4880 2012/03/01 [Refereed][Not invited]
  
• Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure

  Mohd Fairuz Budiman, Weiguo Hu, Makoto Igarashi, Rikako Tsukamoto, Taiga Isoda, Kohei M Itoh, Ichiro Yamashita, Akihiro Murayama, Yoshitaka Okada, Seiji Samukawa

  Nanotechnology 23 (6) 065302 - 065302 0957-4484 2012/02/17 [Refereed][Not invited]
  
• Picosecond transient photoluminescence in high-density Si-nanodisk arrays fabricated using bio-nano-templates

  Takayuki Kiba, Yoshiya Mizushima, Makoto Igarashi, Chi-Hsien Huang, Seiji Samukawa, Akihiro Murayama

  Applied Physics Letters 100 (5) 053117 - 053117 0003-6951 2012/01/30 [Refereed][Not invited]
  
• Plasmonic enhancements of photoluminescence in hybrid Si nanostructures with Au fabricated by fully top-down lithography

  Koudo Nakaji, Hao Li, Takayuki Kiba, Makoto Igarashi, Seiji Samukawa, Akihiro Murayama

  Nanoscale Research Letters 7 (1) 629 - 629 1556-276X 2012 [Refereed][Not invited]
  
• Optical absorption characteristic of highly ordered and dense two-dimensional array of silicon nanodiscs

  Chi-Hsien Huang, Xuan-Yu Wang, Makoto Igarashi, Akihiro Murayama, Yoshitaka Okada, Ichiro Yamashita, Seiji Samukawa

  Nanotechnology 22 (10) 105301 - 105301 0957-4484 2011/03/11 [Refereed][Not invited]
  
• Remote plasma chemical vapor deposition of carbon nanotubes and analysis of plasma effect

  Y. Fukuda, J. Takayama, N. Asaoka, Y. Suda, H. Sugawara, A. Murayama

  IEEE Transactions on Plasma Science 39 3133 - 3139 2011 [Refereed][Not invited]
  
• Defect-free etching process for GaAs/AlGaAs hetero-nanostructure using chlorine/argon mixed neutral beam

  Xuan-Yu Wang, Chi-Hsien Huang, Yuzo Ohno, Mokoto Igarashi, Akihiro Murayama, Seiji Samukawa

  Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena 28 (6) 1138 - 1142 2166-2746 2010/11 [Refereed][Not invited]
  
• Spin Dynamics in ZnO-Based Materials

  I. A. Buyanova, A. Murayama, T. Furuta, Y. Oka, D. P. Norton, S. J. Pearton, A. Osinsky, J. W. Dong, C. W. Tu, W. M. Chen

  Journal of Superconductivity and Novel Magnetism 23 (1) 161 - 165 1557-1939 2010/01 [Refereed][Not invited]
  
• Transfer dynamics of spin-polarized excitons into semiconductor quantum dots

  A. Murayama, T. Furuta, S. Oshino, K. Hyomi, M. Sakuma, I. Souma, D. Dagnelund, I.A. Buyanova, W.M. Chen

  Journal of Luminescence 129 (12) 1927 - 1930 0022-2313 2009/12 [Refereed][Not invited]
  
• Micro-photoluminescence study of electron-spin injection in self-assembled semiconductor quantum dots

  K. Hyomi, M. Sakuma, A. Murayama

  Journal of Luminescence 129 (12) 1715 - 1717 0022-2313 2009/12 [Refereed][Not invited]
  
• SPIN DYNAMICS IN III-V/II-VI: Mn HETEROVALENT QUANTUM WELLS

  A. A. TOROPOV, YA. V. TERENT'EV, A. V. LEBEDEV, P. S. KOP'EV, S. V. IVANOV, T. KOYAMA, K. NISHIBAYASHI, A. MURAYAMA, Y. OKA

  International Journal of Modern Physics B 23 (12n13) 2739 - 2749 0217-9792 2009/05/20 [Refereed][Not invited]
   

  We report on the spectroscopic magnetooptical studies of spin dynamics in diluted magnetic semiconductor (DMS) GaAs / AlGaAs / ZnSe / ZnCdMnSe heterovalent double quantum wells (QW). The transients of circularly polarized photoluminescence in an external magnetic field are detected in the structures with different widths of the GaAs QW. The analysis of the data, performed within the rate-equation model, has allowed separate estimations of the spin relaxation rate of localized electrons and holes. The spin flip of the electrons confined in the DMS ZnCdMnSe QW is faster than 20 ps, whereas the spin flip of the heavy hole localized in the GaAs QW is as long as ~9 ns. The long spin flip of the holes is presumably governed by their strong 3-dimensional localization.
• Magnetic field induced charging effect in a single CdSe quantum dot

  Qijun Ren, Lihui Bai, Akihiro Murayama, Zhanghai Chen, Xuechu Shen

  physica status solidi (b) 246 (4) 791 - 794 0370-1972 2009/04 [Refereed][Not invited]
  
• Exciton broadening and spin dynamics in III-V/II-VI:Mn heterovalent double quantum wells

  A. A. Toropov, Ya. V. Terent’ev, P. S. Kop’ev, S. V. Ivanov, T. Koyama, K. Nishibayashi, A. Murayama, Y. Oka, A. Golnik, J. A. Gaj

  Physical Review B 77 (23) 1098-0121 2008/06/13 [Refereed][Not invited]
  
• Spin-Conserving Tunneling of Excitons in Diluted Magnetic Semiconductor Double Quantum Wells

  Jiho Park, Akihiro Murayama, Izuru Souma, Yasuo Oka, Daniel Dangnelund, Irina A. Buyanova, Weimin Chen

  Japanese Journal of Applied Physics 47 (5) 3533 - 3536 0021-4922 2008/05/16 [Refereed][Not invited]
  
• Spin injection in a coupled system of a diluted magnetic semiconductor Zn0.80Mn0.20Se and self-assembled quantum dots of CdSe

  D. Dagnelund, I.A. Buyanova, W.M. Chen, A. Murayama, T. Furuta, K. Hyomi, I. Souma, Y. Oka

  Superlattices and Microstructures 43 (5-6) 615 - 619 0749-6036 2008/05 [Refereed][Not invited]
  
• Dominant factors limiting efficiency of optical spin detection in ZnO-based materials

  W. M. Chen, I. A. Buyanova, A. Murayama, T. Furuta, Y. Oka, D. P. Norton, S. J. Pearton, A. Osinsky, J. W. Dong

  Applied Physics Letters 92 (9) 092103 - 092103 0003-6951 2008/03/03 [Refereed][Not invited]
  
• Magneto-optical and tunable laser excitation spectroscopy of spin-injection and spin loss from Zn(Cd)MnSe diluted magnetic quantum well to CdSe non-magnetic quantum dots

  D. Dagnelund, I.A. Buyanova, W.M. Chen, A. Murayama, T. Furuta, K. Hyomi, I. Souma, Y. Oka

  Materials Science and Engineering: B 147 (2-3) 262 - 266 0921-5107 2008/02 [Refereed][Not invited]
  
• Efficiency of optical spin injection and spin loss from a diluted magnetic semiconductor ZnMnSe to CdSe nonmagnetic quantum dots

  D. Dagnelund, I. A Buyanova, W. M. Chen, A. Murayama, T. Furuta, K. Hyomi, I. Souma, Y. Oka

  Physical Review B 77 (3) 1098-0121 2008/01/31 [Refereed][Not invited]
  
• Magneto-photoluminescence from single quantum structures of diluted magnetic semiconductor fabricated by e-beam lithography

  A. Murayama, H. Hirano, K. Hyomi, M. Sakuma, I. Souma, Y. Oka

  Journal of Luminescence 122-123 834 - 837 2007 [Refereed][Not invited]
  
• Dynamics of exciton-spin injection, transfer, and relaxation in self-assembled quantum dots of CdSe coupled with a diluted magnetic semiconductor layer of Zn0.80Mn0.20Se

  A. Murayama, T. Furuta, K. Hyomi, I. Souma, Y. Oka, D. Dagnelund, I.A. Buyanova, W.M. Chen

  Physical Review B 75 195308  2007 [Refereed][Not invited]
  
• Spin-resolved magneto-optical study of CdSe single quantum dot

  Z.H. Chen, L.H. Bai, S.H. Huang, H. Xiong, S.C. Shen, I. Souma, K. Hyomi, A. Murayama, Y. Oka

  International Journal of Modern Physics B 21 1549 - 1554 2007 [Refereed][Not invited]
  
• Direct observation of relaxation dynamics of spin-polarized electrons excited at a higher-energy spin-split subband in a diluted magnetic semiconductor quantum well

  K. Saito, J.H. Park, I. Souma, Y. Oka, A. Murayama

  Applied Physics Letters 90 262111  2007 [Refereed][Not invited]
  
• Phonon-induced efficient transfer of spin-polarized excitons in diluted magnetic semiconductor double quantum wells

  J.H. Park, K. Saito, I. Souma, Y. Oka, A. Murayama

  Japanese Journal of Applied Physics 46 7290 - 7293 2007 [Refereed][Not invited]
  
• Ultrafast spin injection from Cd1-xMnxTe magnetic barriers into a CdTe quantum well studied by pump-probe spectroscopy

  I. Aoshima, K. Nishibayashi, I. Souma, A. Murayama, Y. Oka

  Journal of Luminescence 119-120 437 - 441 2006 [Refereed][Not invited]
  
• Pump-probe spectroscopy of spin-injection dynamics in double quantum wells of diluted magnetic semiconductor

  K. Nishibayashi, I. Aoshima, I. Souma, A. Murayama, Y. Oka

  Journal of Luminescence 119-120 433 - 436 2006 [Refereed][Not invited]
  
• Magneto-optical properties in hybrid nanostructures of II-VI diluted magnetic semiconductors with perpendicular ferromagnetic films

  M. Sakuma, K. Hyomi, I. Souma, A. Murayama, Y. Oka

  Physica Status Solidi (b) 243 902 - 905 2006 [Refereed][Not invited]
  
• Magneto-photoluminescence spectroscopy of ZnMnTe/ZnMgTe spin superlattice

  L.H. Bai, Z.H. Chen, F.Z. Wang, S.H. Huang, H. Xiong, I. Souma, A. Murayama, Y. Oka, S.C. Shen

  Journal of Luminescence 119-120 541-545  2006 [Refereed][Not invited]
  
• Efficient spin injection into self-assembled quantum dots via LO-phonon-assisted resonant electron tunneling

  A. Murayama, T. Asahina, K. Nishibayashi, I. Souma, Y. Oka

  Applied Physics Letters 88 023114  2006 [Refereed][Not invited]
  
• Coupling of quantum states in a single CdSe/ZnSe quantum dot molecule

  H. Xiong, Z.H. Chen, K. Hyomi, I. Souma, Y.N. Zhang, L.X. Sun, Q.J. Ren, L.H. Bai, S.H. Huang, F.Z. Wang, A. Murayama, Y. Oka, S.C. Shen

  Journal of Luminescence 119-120 193 - 197 2006 [Refereed][Not invited]
  
• Transient photoluminescence spectroscopy of spin injection dynamics in double quantum wells of diluted magnetic semiconductors

  K. Kayanuma, K. Seo, K. Nishibayashi, A. Murayama, Y. Oka, I.A. Buyanova, W.M. Chen

  Journal of Luminescence 119-120 418 - 422 2006 [Refereed][Not invited]
  
• Nanoscale magnet for semiconductor spintronics

  A. Murayama, M. Sakuma

  Applied Physics Letters 88 122504  2006 [Refereed][Not invited]
  
• Dynamical spin separation induced by spin-dependent type-II band alignment in a diluted magnetic double quantum well

  T. Koyama, K. Kayanuma, I. Souma, A. Murayama, Y. Oka

  Applied Physics Letters 88 212106  2006 [Refereed][Not invited]
  
• Fabrication and magneto-optical properties of nanostructures of diluted magnetic semiconductors integrated with glass thin films

  A. Murayama, K. Hyomi, M. Sakuma, I. Souma

  Japanese Journal of Applied Physics 45 5311 - 5316 2006 [Refereed][Not invited]
  
• Spin-injection dynamics in a magnetic double quantum well studied by pump-probe absorption spectroscopy

  K. Nishibayashi, I. Souma, A. Murayama, Y. Oka

  Applied Physics Letters 88 211108  2006 [Refereed][Not invited]
  
• Spin dynamics in a diluted magnetic semiconductor quantum well studied by pump-probe absorption spectroscopy; Magnetic-field-induced suppression of electron-spin relaxation

  A. Murayama, K. Seo, K. Nishibayashi, I. Souma, Y. Oka

  Applied Physics Letters 88 261105  2006 [Refereed][Not invited]
  
• Density-dependent dynamics of exciton magnetic polarons in ZnMnSe/ZnSSe type II quantum wells

  A.A. Toropov, Ya.V. Terent’ev, S.V. Sorokin, S.V. Ivanov, T. Koyama, K. Nishibayashi, A. Murayama, Y. Oka, J.P. Bergman, I.A. Buyanova, W.M. Chen, B. Monemar

  Physical Review B 73 245335  2006 [Refereed][Not invited]
  
• Magnetic-field-dependent type-II transition induced by resonant electron tunneling from a diluted magnetic semiconductor quantum well into self-assembled quantum dots

  A. Murayama, T. Asahina, K. Nishibayashi, I. Souma, Y. Oka

  Journal of Applied Physics 100 084327  2006 [Refereed][Not invited]
  
• Effect of momentum relaxation on exciton spin dynamics in diluted magnetic semiconductor ZnMnSe/CdSe superlattices

  I.A. Buyanova, G.Yu, Rudko, W.M. Chen, K. Kayanuma, A. Murayama, Y. Oka, A.A. Toropov, S.V. Sorokin, S.V. Ivanov

  Physical Review B 71 165203  2005 [Refereed][Not invited]
  
• Giant Zeeman effects and spin dynamics of excitons in dense self-organized quantum dots of CdSe and Cd1-xMnxSe

  I. Souma, K. Kayanuma, K. Hyomi, K. Nishibayashi, A. Murayama, Y. Oka

  Journal of Superconductivity: incorporating Novel Magnetism 18 219 - 222 2005 [Refereed][Not invited]
  
• Identification of a dominant mechanism for optical spin injection from a diluted magnetic semiconductor: Spin-conserving energy transfer via localized excitations

  W.M. Chen, I.A. Buyanova, K. Kayanuma, K. Nishibayashi, K. Seo, A. Murayama, Y. Oka, A.A. Toropov, A.V. Lebedev, S.V. Sorokin, S.V. Ivanov

  Physical Review B 72 073206  2005 [Refereed][Not invited]
  
• Efficient spin relaxation in InGaN/GaN and InGaN/GaMnN quantum wells: An obstacle to spin detection

  W.M. Chen, I.A. Buyanova, K. Nishibayashi, K. Kayanuma, K. Seo, A. Murayama, Y. Oka, G. Thaler, R. Frazier, C.R. Abernathy, F.Ren, S.J. Pearton, C.-C. Pan, G.-T. Chen, J.-I. Chyi

  Applied Physics Letters 87 192107 - 192109 2005 [Refereed][Not invited]
  
• Giant magneto-optical properties in hybrid nano-structures of diluted magnetic semiconductors with ferromagnetic Co wires

  M. Sakuma, K. Hyomi, I. Souma, A. Murayama, Y. Oka

  Journal of Superconductivity: incorporating Novel Magnetism 18 325- - 329 2005 [Refereed][Not invited]
  
• Spin injection processes in ZnSe-based double quantum dots of diluted magnetic semiconductors

  T. Tomita, A. Uetake, T. Asahina, K. Kayanuma, A. Murayama, Y. Oka

  Journal of Superconductivity: incorporating Novel Magnetism 18 405 - 410 2005 [Refereed][Not invited]
  
• Pump-probe spectroscopy of exciton spin injection process in diluted magnetic quantum wells

  K. Nishibayashi, K. Seo, K. Kayanuma, T. Tomita, A. Murayama, Y. Oka

  Journal of Superconductivity: incorporating Novel Magnetism 18 399 - 404 2005 [Refereed][Not invited]
  
• Transient spectroscopy of optical spin injection in ZnMnSe/ZnCdSe quantum structures

  I.A. Buyanova, W.M. Chen, K. Kayanuma, Z.H. Chen, A. Murayama, Y. Oka, A.A. Toropov, S.V. Sorokin, A.V. Kebedev, S.V. Ivanov

  Journal of Superconductivity: incorporating Novel Magnetism 18 371 - 373 2005 [Refereed][Not invited]
  
• Light scattering study on hybrid structures of Zn1-x-yCdxMnySe quantum wells with ferromagnetic Co wires

  M. Sakuma, K. Hyomi, I. Souma, A. Murayama, Y. Oka

  Physica Status Solidi (b) 241 664 - 667 2004 [Refereed][Not invited]
  
• Dynamics in magneto-optical properties of digital magnetic Zn1-xCdxSe quantum wells

  E. Nakayama, K. Kayanuma, T. Tomita, A. Murayama, Z.H. Chen, Y. Oka

  Physica E 21 1027 - 1031 2004 [Refereed][Not invited]
  
• Interface magnetic properties of MnSe digitally doped in ZnSe-based quantum wells

  A. Murayama, E. Nakayama, T. Tomita, I. Souma, Y. Oka

  Journal of Applied Physics 95 7408 - 7410 2004 [Refereed][Not invited]
  
• Dynamic magnetic properties of epitaxial MnAs thin films studied by spin-wave Brillouin scattering

  A. Murayama, K. Hyomi, M. Sakuma, Y. Oka, J. Okabayashi, M. Mizuguchi, H. Kuramochi, H. Akinaga

  Journal of Applied Physics 95 6619 - 6621 2004 [Refereed][Not invited]
  
• Giant Zeeman effect of excitons in a hybrid nanostructure of diluted magnetic semiconductor quantum well sandwiched in Co wires

  M. Sakuma, K. Hyomi, I. Souma, A. Murayama, Y. Oka

  Applied Physics Letters 85 6203 - 6205 2004 [Refereed][Not invited]
  
• Efficient spin depolarization in ZnCdSe spin detector: an important factor limiting optical spin injection efficiency in ZnMnSe/ZnCdSe spin light-emitting structures

  W.M. Chen, I.A. Buyanova, K. Kayanuma, Z.H. Chen, A. Murayama, Y. Oka, A.A. Toropov, S.V. Sorokin, S.V. Ivanov, P.S. Kop'e

  Applied Physics Letters 85 5260 - 5262 2004 [Refereed][Not invited]
  
• Effects of digital doping of Mn on giant magneto-optical properties of Zn1-xMnxSe quantum wells

  E. Nakayama, T. Uchida, I. Souma, Z.H. Chen, A. Murayama, Y. Oka

  Journal of Superconductivity: incorporating Novel Magnetism 16 407 - 410 2003 [Refereed][Not invited]
  
• Magnetic-field-induced level crossing and the spin dynamics of excitons in Zn1-xMnxTe/ZnTe quantum wells

  S. Shirotori, K. Kayanuma, T. Tomita, Z.H. Chen, M.C. Debnath, I. Souma, A. Murayama, Y. Oka

  Journal of Superconductivity: incorporating Novel Magnetism 16 457 - 460 2003 [Refereed][Not invited]
  
• Submicron scale hybrid structures of diluted magnetic semiconductor quantum wells with ferromagnetic Co wires

  M. Sakuma, K. Hyomi, I. Souma, A. Murayama, Y. Oka

  Journal of Applied Physics 94 6423 - 6429 2003 [Refereed][Not invited]
  
• Spin dynamics of excitons and magnetic ions in Cd1-xMnxTe/Cd1-yMgyTe quantum wells

  Z.H. Chen, H. Sakurai, K .Seo, K. Kayanuma, T. Tomita, A. Murayama, Y. Oka

  Physica B 340-342 890 - 894 2003 [Refereed][Not invited]
  
• Spin injection and spin switching of excitons in coupled quantum wells of diluted magnetic semiconductors

  K. Kayanuma, S. Shirotori, Z.H. Chen, T. Tomita, A. Murayama, Y. Oka

  Physica B 340-342 882 - 885 2003 [Refereed][Not invited]
  
• Subpicosecond dynamical renormalization of spin-polarized electron-hole plasma in Cd1-xMnxTe

  Z.H. Chen, H. Sakurai, T. Tomita, K. Kayanuma, A. Murayama, Y. Oka

  Physica E 21 1022 - 1026 2003 [Refereed][Not invited]
  
• Exciton recombination processes in Cd1-xMnxSe/ZnSe quantum dots under magnetic fields

  K. Shibata, E. Nakayama, I. Souma, A. Murayama, Y. Oka

  Physica Status Solidi (b) 229 473 - 476 2002 [Refereed][Not invited]
  
• Spin-dependent carrier confinements and radiative recombinations in Zn1-xMnxTe/Zn1-yMgyTe spin superlattices

  M.C. Debnath, Z.H. Chen, I. Souma, K. Sato, A. Murayama, Y. Oka

  Physica Status Solidi (b) 229 695 - 699 2002 [Refereed][Not invited]
  
• Exciton spin injection in CdTe/Cd1-xMnxTe double quantum wells

  K. Kayanuma, M.C. Debnath, I. Souma, Z.H. Chen, A. Murayama, M. Kobayashi, H. Miyazaki, Y. Oka

  Physica Status Solidi (b) 229 761 - 764 2002 [Refereed][Not invited]
  
• Surface magnetic anisotropy of Co(0001) and effects of ultrathin Cu-overlayers studied by in-situ spin-wave Brillouin light scattering

  K. Hyomi, A. Murayama, Y. Oka, U. Hiller, C.M. Falco

  Applied Physics Letters 80 282 - 284 2002 [Refereed][Not invited]
  
• Magneto-optical properties and exciton dynamics in diluted magnetic semiconductor nanostructures

  Y. Oka, K. Kayanuma, S. Shirotori, A. Murayama, I. Souma, Z.H. Chen

  Journal of Luminescence 100 175 - 190 2002 [Refereed][Not invited]
  
• Excitonic Properties and Dynamics in Diluted Magnetic Semiconductor Quantum Nanostructures

  Y. Oka, K. Kayanuma, E. Nakayama, S. Shiratori, I. Souma, T. Tomita, Z.H. Chen, A. Murayama

  Nonlinear Optics 29 491 - 499 2002 [Refereed][Not invited]
  
• Brillouin study of long-wavelength spin waves in quasimonatomic Co films with uniaxial perpendicular magnetic anisotropy

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falco

  Physical Review B 61 8984 - 8992 2000 [Refereed][Not invited]
  
• Micro magnetic study of CoPt-SiO2 granular films by the spin-wave Brillouin scattering

  A. Kikitsu, A. Murayama, K. Hyomi, C.M. Falco

  Journal of Applied Physics 87 6944 - 6946 2000 [Refereed][Not invited]
  
• Anomalous magneto-optical properties of EuTe induced by magnetic polarons

  Z.H. Chen, W. Heiss, I. Souma, A. Murayama, Y. Oka

  Journal of Superconductivity: incorporating Novel Magnetism 16 403 - 405 2000 [Refereed][Not invited]
  
• Magnetic inhomogeneity in ultrathin Co films studied by spin-wave Brillouin scattering

  K. Hyomi, A. Murayama, J. Eickmann, C.M. Falco

  Journal of Magnetism and Magnetic Materials 198-199 528 - 530 1999 [Refereed][Not invited]
  
• Perpendicular magnetic anisotropy in Au/Co/Au(111) sandwiched films: Interface anisotropy and effect of strain

  K. Hyomi, A. Murayama, J. Eickmann, C.M. Falco

  Journal of Magnetism and Magnetic Materials 198-199 378 - 380 1999 [Refereed][Not invited]
  
• Low frequency excitation of spin-wave Brillouin scattering in ultra-thin Co/Au(111) films with a perpendicular anisotropy

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falc

  Journal of Magnetism and Magnetic Materials 198-199 372 - 374 1999 [Refereed][Not invited]
  
• Spin-wave Brillouin scattering in quasimonatomic Co films

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falco

  Journal of Applied Physics 85 5051 - 5053 1999 [Refereed][Not invited]
  
• Strain dependence of the interface perpendicular magnetic anisotropy in epitaxial Co/Au/Cu(111) films

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falco

  Physical Review B 60 15245 - 15250 1999 [Refereed][Not invited]
  
• Enhancement of elastic-light-scattering due to the magnetization instability in ultrathin magnetic films

  A. Murayama, K. Hyomi, C.M. Falco

  Physical Review B 60 6281 - 6284 1999 [Refereed][Not invited]
  
• Effect of an ultrathin Au interlayer at a Co/Cu(111) interface on the magnetic properties

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falco

  Journal of Applied Physics 83 613 - 615 1998 [Refereed][Not invited]
  
• Effect of an Au underlayer on perpendicular magnetic anisotropy in Au/Co/Au(111) sandwich films

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falco

  IEEE Transactions on Magnetics 34 1198 - 1200 1998 [Refereed][Not invited]
  
• Underlayer-induced perpendicular magnetic anisotropy in ultrathin Co/Au/Cu(111) films: A spin-wave Brillouin scattering study

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falco

  Physical Review B 58 8596 - 8604 1998 [Refereed][Not invited]
  
• Grain structure and magnetic clustering in SiO2 added CoNiPt granular films

  A. Murayama, K. Hyomi, K. Ohshima, M. Miyamura, M. Maekawa, S. Kondoh

  Journal of Applied Physics 81 3925 - 3927 1997 [Refereed][Not invited]
  
• Spin-wave Brillouin study of ultra-thin Co/Au(111) films with perpendicular magnetic anisotropy

  A. Murayama, K. Hyomi, J. Eickmann, C.M. Falco

  Journal of Applied Physics 82 6186 - 6192 1997 [Refereed][Not invited]
  
• Magnetic interaction and remanence properties in CoNiPt(SiO2) granular films for high-density longitudinal recording

  A. Murayama, K. Ohshima, M. Miyamura, M. Maekawa, S. Kondoh

  Journal of Applied Physics 79 7916 - 7919 1996 [Refereed][Not invited]
  
• Effect of oxide addition on magnetic and structural properties of CoNiPt alloy films

  A. Murayama, S. Kondoh, M. Miyamura

  Journal of Applied Physics 75 6147 - 6149 1994 [Refereed][Not invited]
  
• Magnetic and structural properties of CoNiPt(SiO2) alloy films for high-density longitudinal recording

  A. Murayama, M. Miyamura, S. Kondoh

  Journal of Applied Physics 76 5361 - 5370 1994 [Refereed][Not invited]
  
• Chemical segregation in CoNiPt(SiO2) alloy film

  A. Murayama, M. Miyamura, S. Kondoh

  Applied Physics Letters 65 1186 - 1188 1994 [Refereed][Not invited]
  
• Brillouin spectroscopy of spin waves in sputtered CoPt alloy films and Co/Pt/Co multilayered films

  A. Murayama, M. Miyamura, K. Nishiyama, K. Miyata, Y. Oka

  Journal of Applied Physics 69 5661 - 5663 1991 [Refereed][Not invited]
  
• Interlayer exchange coupling in Co/Cr/Co double-layered recording films studied by spin-wave Brillouin scattering

  A. Murayama, M. Miyamura, K. Miyata, Y. Oka

  IEEE Transactions on Magnetics 27 5064 - 5066 1991 [Refereed][Not invited]
  
• Brillouin study of spin waves in sputtered CoNiPt alloy films

  A. Murayama, M. Miyamura, S. Ishikawa, Y. Oka

  Journal of Applied Physics 67 410 - 413 1990 [Refereed][Not invited]
  
• Characterization of evaporated amorphous WO3 films by Raman and FTIR spectroscopies

  Y. Shigesato, A. Murayama, T. Kamimori, K. Matsuhiro

  Applied Surface Science 33/34 804 - 811 1988 [Refereed][Not invited]
  
• Picosecond spectroscopy of Raman scattering and luminescence from rhodamine 6G molecules adsorbed on Ag surfaces

  A. Murayama, Y. Oka, H. Fujisaki

  Surface Science 158 222 - 228 1986 [Refereed][Not invited]
  
• Picosecond transient spectroscopy of fluorescence in rhodamine 6G adsorbed electrochemically on Ag surface

  A. Murayama, Y. Oka, H. Fujisaki

  Solid State Communications 55 91 - 95 1985 [Refereed][Not invited]
  

Books etc

• 物性科学 : 理工学基礎

  坂田, 亮, 村山, 明宏 
  培風館 2022/07 (ISBN: 9784563067922) xiv, 327p
• 量子ドット（エレクトロニクスの最前線）

  村山明宏 (Contributor自己組織化量子ドットにおける高効率スピン注入とその制御技術)
  株式会社エヌ・ティー・エス 2011/03
• 機能性ガラス・ナノガラスの最新技術

  村山明宏, 岡泰夫 (Contributor磁性半導体ナノガラスの作製)
  ㈱エヌ・ティー・エス 2006/07
• Optical properties of condensed matter and applications

  A. Murayama, Y. Oka (ContributorOptical Properties and Spin Dynamics of Diluted Magnetic Semiconductor Nanostructures)
  John Wiley 2006 (ISBN: 0470021926) xiv, 434 p.

Presentations

• Temperature dependence of photoluminescence properties of dilute nitride InGaAsN quantum dots  [Not invited]

  A. Morita, S. Hiura, J. Takayama, A. Murayama

  36th International Microprocesses and Nanotechnology Conference (MNC 2023)  2023/11
• Room-temperature electron spin transport to InAs quantum dots using a dilute nitride GaNAs/GaAs superlattice barrier  [Not invited]

  M. Hosoe, S. Sato, S. Hiura, J. Takayama, A. Murayama

  36th International Microprocesses and Nanotechnology Conference (MNC 2023)  2023/11
• Circularly polarized light detection characteristics of spin photodiode based on a dilute nitride GaNAs spin filter  [Not invited]

  T. Hioki, K. Etou, S. Hiura, J.Takayama, A. Subagyo, K. Sueoka, A. Murayama

  36th International Microprocesses and Nanotechnology Conference (MNC 2023)  2023/11
• Room temperature operation of spin-functional optical devices based on 0D-2D hybrid semiconductor nanostructures  [Invited]

  A. Murayama, S. Hiura

  36th International Microprocesses and Nanotechnology Conference (MNC 2023)  2023/11
• Electric-field effects on optical spin polarization in III-V semiconductor quantum-dot-superlattice hybrid nanostructure  [Not invited]

  H. Kise, S. Park, S. Hiura, J. Takayama, K. Sueoka, A. Murayama

  The 9th International Symposium on Organic and Inorganic Electronic Materials and Related Nanotechnologies (EM-NANO 2023)  2023/06
• Bias voltage and temperature dependence of electron-spin polarization in InAs quantum dots tunnel-coupled with a GaNAs quantum well  [Not invited]

  S. Park, H. Kise, S. Hiura, J. Takayama, K. Sueoka, A. Murayama

  2022 International Conference on Solid State Devices and Materials (SSDM2022)  2022/09
• Room-temperature operation characteristics of a spin-polarized light-emitting diode using InAs quantum dots tunnel-coupled with GaNAs  [Not invited]

  K. Etou, S. Hiura, J. Takayama, A. Subagyo, K. Sueoka, A. Murayama

  2022 International Conference on Solid State Devices and Materials (SSDM2022)  2022/09
• Structural and optical properties of InAs quantum dots capped with GaAs grown at different rates  [Not invited]

  S. Izumi, S. Hiura, J. Takayama, A. Murayama

  The 22nd International Vacuum Congress (IVC-22)  2022/09
• Thickness effects of dilute GaAs nitride quantum wells on optical spin properties of tunnel-coupled InAs quantum dots  [Not invited]

  S. Sato, M. Hosoe, S. Hiura, J. Takayama, A. Murayama

  The 22nd International Vacuum Congress (IVC-22)  2022/09
• Temperature effects on performances of a spin-polarized light emitting diode using p-doped InGaAs quantum dots  [Not invited]

  K. Etou, S. Hiura, J. Takayama, S. Park, A. Subagyo, K. Sueoka, A. Murayama

  2021 International Conference on Solid State Devices and Materials (SSDM2021)  2021
• Optical spin properties of InAs quantum dots tunnel-coupled with dilute nitride GaNAs  [Not invited]

  S. Sato, Y. Nakamura, S. Park, S. Hiura, J. Takayama, A. Murayama

  2021 International Conference on Solid State Devices and Materials (SSDM2021)  2021
• Electric-field control of electron-spin polarization degree at room temperature in opto-spintronic device using InGaAs quantum dots  [Not invited]

  S. Park, S. Hiura, H. Chen, J. Takayama, K. Sueoka, A. Murayama

  2021 International Conference on Solid State Devices and Materials (SSDM2021)  2021
• Fabrication of p-doped quantum dot spin-polarized light-emitting diodes  [Not invited]

  K. Etou, S. Hiura, J. Takayama, A. Murayama

  2020 International Conference on Solid State Devices and Materials (SSDM2020)  2020/09
• Highly efficient electron-photon spin conversion using InGaAs quantum dots with p-doped capping barrier  [Not invited]

  S. Sato, S. Hiura, J. Takayama, A. Murayama

  2020 International Conference on Solid State Devices and Materials (SSDM2020)  2020/09
• Electron-spin dynamics in tunnel-coupled structures of InGaAs well and dot with different p-doping concentrations applied with electric field  [Not invited]

  S. Park, H. Chen, S. Hiura, J. Takayama, A. Murayama

  2020 International Conference on Solid State Devices and Materials (SSDM2020)  2020/09
• Spin relaxation property after spin transfer from a semiconductor superlattice barrier to quantum dots  [Not invited]

  S. Hatakeyama, S. Hiura, J. Takayama, A. Murayama

  2020 International Conference on Solid State Devices and Materials (SSDM2020)  2020/09
• Quantum spin transport to self-assembled InGaAs quantum dots through AlGaAs/GaAs superlattice  [Not invited]

  S. Hiura, J. Takayama, T. Kiba, A. Murayama

  Materials Research Meeting (MRM2019)  2019/12
• Size-modulation-induced spin amplification in quantum nanocolumns  [Not invited]

  S. Hiura, S. Saito, J. Takayama, T. Kiba, A. Murayama

  7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano2019)  2019/09
• Temperature dependence of modal gain at excited states in high-density InGaAs quantum dots by variable stripe length method  [Not invited]

  A. Ohtake, S. Hiura, J. Takayama, A. Murayama

  7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano2019)  2019/09
• Temperature-persistent spin relaxation in InGaAs/GaAs dots-in-well structure  [Not invited]

  M. Takishita, S. Hiura, J. Takayama, A. Murayama

  7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano2019)  2019/09
• Electric-field-effect optical spin-injection device using p-doped InGaAs quantum dots  [Not invited]

  S. Park, H. Chen, S. Hiura, J. Takayama, A. Murayama

  7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano2019)  2019/09
• Temperature-dependent spin dynamics in InGaAs quantum dots embedded with GaAs capping layer grown at low temperature  [Not invited]

  Y. Nakamura, S. Hiura, S. Sato, J. Takayama, A. Murayama

  7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano2019)  2019/09
• P-doping effects on temperature-dependent spin dynamics in InGaAs quantum dots  [Not invited]

  S. Sato, S. Hiura, J. Takayama, A. Murayama

  7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano2019)  2019/09
• Lateral electronic coupling among self-assembled semiconductor quantum dots promoted by adjoining tunnel-coupled quantum-well potentials  [Not invited]

  J. Takayama, S. Hiura, K. Takeishi, T. Kiba, A. Murayama

  Compound Semiconductor Week 2019 (CSW2019)  2019/05
• Effects of growth temperature of a capping layer on excited spin properties of In0.5Ga0.5As quantum dots  [Not invited]

  Y. Nakamura, S. Hiura, S. Sato, J. Takayama, A. Murayama

  Compound Semiconductor Week 2019 (CSW2019)  2019/05
• Effects of p-doping on excited spin states and the dynamics in InGaAs quantum dots  [Not invited]

  S. Sato, M. Murakami, Y. Nakamura, S. Hiura, J. Takayama, A. Murayama

  Compound Semiconductor Week 2019 (CSW2019)  2019/05
• Electric-field control of optical-spin injection from an InGaAs quantum well to p-doped quantum dots  [Not invited]

  S. Park, H. Chen, J. Takayama, S. Hiura, A. Murayama

  Compound Semiconductor Week 2019 (CSW2019)  2019/05
• Spin-conserved electron transport to InGaAs quantum dots through GaAs/AlGaAs superlattice  [Not invited]

  S. Hiura, J. Takayama, T. Kiba, A. Murayama

  Compound Semiconductor Week 2019 (CSW2019)  2019/05
• Temperature Dependence of Interdot Spin Dynamics in Laterally Coupled InGaAs Quantum Dots  [Not invited]

  S. Sato, S. Hiura, J. Takayama, A. Murayama

  31st International Microprocesses and Nanotechnology Conference (MNC 2018)  2018/11
• Electric-Field Optical Device Controlling Electron-Spin Polarity of InGaAs Quantum Dots  [Not invited]

  H. Chen, J. Takayama, S. Hiura, K. Sueoka, A. Murayama

  31st International Microprocesses and Nanotechnology Conference (MNC 2018)  2018/11
• Temperature-Persistent High Spin Polarization and Its Dynamics in InGaAs Quantum Dots Embedded in a GaAs Quantum Well  [Not invited]

  M. Takishita, S. Hiura, J. Takayama, A. Murayama

  31st International Microprocesses and Nanotechnology Conference (MNC 2018)  2018/11
• Modal Gain at Excited States in High-Density InGaAs Quantum Dots Investigated by Variable Stripe Length Method  [Not invited]

  A. Ohtake, S. Hiura, A. Washida, J. Takayama, A. Murayama

  31st International Microprocesses and Nanotechnology Conference (MNC 2018)  2018/11
• Optical Study on Thermal Activation Processes of Carrier Dynamics in In0.3Ga0.7N Nanodisks  [Not invited]

  Y. Chen, T. Kiba, J. Takayama, A.Higo, T. Tanikawa, S. Samukawa, A. Murayama

  31st International Microprocesses and Nanotechnology Conference (MNC 2018)  2018/11
• Excited Spin Engineering of In0.5Ga0.5As Quantum Dots by an Adjacent Two-Dimensional In0.1Ga0.9As Quantum Well Potential  [Not invited]

  S. Hiura, K. Takeishi, J. Takayama, T. Kiba, A. Murayama

  31st International Microprocesses and Nanotechnology Conference (MNC 2018)  2018/11
• Effects of electrical field on circularly polarized photoluminescence in InGaAs-based coupled nanostructures of quantum dots and a well  [Not invited]

  H. Chen, J. Takayama, S. Hiura, A. Subagyo, K. Sueoka, A. Murayama

  The 12th International Conference on Excitonic and Photonic Processes in Condensed Matter and Nano Materials (EXCON2018)  2018/07
• High-temperature carrier dynamics responsible for a non-radiative process in InGaN nanodisks fabricated by top-down nanotechnology  [Not invited]

  Y. Chen, T. Kiba, J. Takayama, A. Higo, T. Tanikawa, S. Samukawa, A. Murayama

  The 12th International Conference on Excitonic and Photonic Processes in Condensed Matter and Nano Materials (EXCON2018)  2018/07
• Temperature-dependent spin dynamics in InGaAs/GaAs dots-in-well structure  [Not invited]

  M. Takishita, K. Takeishi, S. Hiura, J. Takayama, A. Washida, A. Ohtake, S. Saito, A. Murayama

  The 12th International Conference on Excitonic and Photonic Processes in Condensed Matter and Nano Materials (EXCON2018)  2018/07
• Influence of vertical interdot coupling on energy-dependent modal gain of InGaAs quantum dots  [Not invited]

  A. Ohtake, A. Washida, S. Hiura, J. Takayama, M. Takishita, S. Saito, A. Murayama

  The 12th International Conference on Excitonic and Photonic Processes in Condensed Matter and Nano Materials (EXCON2018)  2018/07
• Persistent high spin polarization induced by interdot spin transfer among coupled excited states of InGaAs quantum dots  [Not invited]

  S. Hiura, K. Takeishi, A. Washida, J. Takayama, A. Ohtake, M. Takishita, S. Saito, A. Murayama

  The 12th International Conference on Excitonic and Photonic Processes in Condensed Matter and Nano Materials (EXCON2018)  2018/07
• Spin transfer dynamics in III-V compound semiconductor quantum dots integrated with layered quantum structures  [Invited]

  Akihiro Murayama

  The 30th International Microprocesses and Nanotechnology Conference (MNC2017)  2017/11
• Emission Enhancement and its dynamics of Alq3 with Surface Plasmon Resonance of Ag Nanoparticles  [Not invited]

  K. Masui, T. Kiba, A. Sato, K. Yanome, M. Kawamura, Y. Abe, K. H. Kim, H. D. Kim, J. Takayama, A. Murayama

  International Thin Films Conference  2017/10
• Time-resolved Photoluminescence Study of Alq3 Thin Film with Plasmonic Ag Nanotriangle Array Fabricated by Nanosphere Lithography  [Not invited]

  K. Yanome, T. Kiba, K. Masui, M. Kawamura, Y. Abe, K. H. Kim, M. Takase, J. Takayama, A. Murayama

  International Thin Films Conference  2017/10
• Optically coupled excitons in a single coupled-quantum-dot structure via dipole-dipole interaction  [Not invited]

  H. D. Kim, A. Murayama, K. Kyhm, R. A. Taylor, J. S. Kim

  20th International Conference on Electron Dynamics in Semiconductors, Optoelectronics and Nanostructures (EDISON20)  2017/06
• Fabrication of GaAs quantum nanodisk by bio-template, neutral beam etching, and asymmetric AlGaAs barrier regrowth and its optical response  [Not invited]

  A. Higo, Y. Chen, T. Kiba, C. Thomas, J. Takayama, A. Imoto, S. Miyazaki, T. Kamikawa, M. Tanaka, I. Yamashita, Y. Wang, H. Sodabanlu, M. Sugiyama, Y. Nakano, A. Murayama, S. Samukawa

  SPIE Photonics WEST 2017  2017/02
• Spin-Functional Photoelectric Conversion Utilizing III-V Compound Semiconductor Quantum Dots  [Invited]

  Akihiro Murayama

  6th Annual World Congress of Nano Science & Technology (Nano-S&T 2016)  2016/10
• Pump-probe study of temperature-dependent spin relaxation in GaAs quantum disks fabricated by fully top-down lithography using Bio-templates  [Not invited]

  T. Kiba, T. Tanaka, A. Higo, C. Thomas, Y. Tamura, S. Samukawa, A. Murayama

  16th IEEE International Conference on Nanotechnology  2016/08
• Electric-field control of spin states in InGaAs-based coupled nanostructures of quantum dots and well  [Not invited]

  Y. Akei, J. Takayama, K. Takeishi, K. Itabashi, M. Urabe, A. Murayama

  16th IEEE International Conference on Nanotechnology  2016/08
• Ultrahigh-density self-assembled quantum dots of InGaAs and suppression of optical state-filling effect  [Not invited]

  M. Urabe, K. Takeishi, J. Takayama, K. Itabashi, S.L. Chen, A. Murayama

  16th IEEE International Conference on Nanotechnology  2016/08
• Transient photoluminescence in InGaN nano-disks fabricated by nano-scale neutral-beam etching utilizing bio-nano templates  [Not invited]

  Y. Chen, S.L. Chen, T. Kiba, C.Y. Lee, C. Thomas, Y.C. Lai, A. Higo, S. Samukawa, A. Murayama

  16th IEEE International Conference on Nanotechnology  2016/08
• Growth optimization of spin-transport barriers used for spin-polarized light-emitting diodes based on InGaAs quantum dots  [Not invited]

  K. Itabashi, K. Takeishi, M. Urabe, J. Takayama, S.L. Chen, A. Murayama

  16th IEEE International Conference on Nanotechnology  2016/08
• Transient photoluminescence study on spin dynamics in InGaAs-based coupled nanostructures of quantum dots with quantum wells  [Not invited]

  K. Takeishi, S.L. Chen, J. Takayama, K. Itabashi, M. Urabe, A. Murayama

  16th IEEE International Conference on Nanotechnology  2016/08
• InGaN Quantum Nanodisks fabrication by Bio-Template and Neutral Beam etching  [Not invited]

  Y.C. Lai, A. Higo, C. Thomas, C.Y. Lee, T. Tanikawa, K. Shojiki, S. Kuboya, R. Katayama, T. Kiba, I. Yamashita, A. Murayama, P. Yu, Seiji Samukawa

  American Vacuum Society – AVS 62nd International Symposium and Exhibition  2015/10
• Room temperature operation of GaAs/AlGaAs quantum nanodisks light emitting diodes fabricated by fusion of bio-template and neutral beam etching  [Not invited]

  Y.C. Lai, A. Higo, C. Thomas, T. Kiba, J. Takayama, M. Sugiyama, Y. Nakano, P. Yu, A. Murayama, S. Samukawa

  47th International Conference on Solid State Devices and Materials  2015/09
• Phonon-assisted efficient spin injection in InGaAs quantum well-quantum dot tunnel-coupled structures  [Not invited]

  S.L. Chen, T. Kiba, J. Takayama, A. Murayama

  47th International Conference on Solid State Devices and Materials  2015/09
• Effect of remote doping on photoluminescence and carrier spin dynamics in InGaAs quantum dots  [Not invited]

  D. Yamazaki, S.L. Chen, J. Takayama, A. Murayama

  47th International Conference on Solid State Devices and Materials  2015/09
• High-density self-assembled quantum dots of InGaAs for ultrafast and efficient spin injection  [Not invited]

  J. Takayama, T. Kiba, T. Yamamura, D. Yamazaki, S.L. Chen, A. Murayama

  47th International Conference on Solid State Devices and Materials  2015/09
• Temperature dependences of spin-injection dynamics and spin-polarized electroluminescence in InGaAs quantum dots  [Not invited]

  Y. Nomura, Y. Akei, J. Takayama, T. Kiba, A. Subagyo, T. Yamamura, D. Yamazaki, K. Sueoka, A. Murayama

  47th International Conference on Solid State Devices and Materials  2015/09
• Fabrication of InGaN/GaN nanodisk structure by using bio-template and neutral beam etching process  [Not invited]

  Y.C. Lai, A. Higo, C.Y. Lee, C. Thomas, T. Tanikawa, K. Shojiki, S. Kuboya, R. Katayama, T. Kiba, P. Yu, I. Yamashita, A. Murayama, S. Samukawa

  15th International IEEE Conference on Nanotechnology  2015/07
• Optical study of temperature-dependent spin injection and relaxation dynamics in InGaAs quantum well-quantum dot tunnel-coupled structure  [Not invited]

  S.L. Chen, T. Kiba, X.J. Yang, J. Takayama, A. Murayama

  17th International Conference on Modulated Semiconductor Structures  2015/07
• Top-down InGaAs/GaAs nanopillars fabrication using a bio-nano process and a neutral beam etching process  [Not invited]

  C. Thomas, K. Yoshikawa, C.Y. Lee, Y. Tamura, A. Higo, T. Kiba, A. Murayama, I. Yamashita, S. Samukawa

  American Vacuum Society – AVS 61st. International Symposium and Exhibition  2014/11
• Crystal growth of III-V compound semiconductor nanostructures and transient spin-related optical phenomena  [Invited]

  Akihiro Murayama

  Collaborative Conference on Crystal Growth (3CG2014)  2014/11
• Suppression of exciton-spin relaxation induced by artificial lateral quantum confinement in GaAs  [Not invited]

  T. Kiba, T. Tanaka, Y. Tamura, C. Thomas, T. Kaizu, Y. Okada, S. Samukawa, A. Murayama

  18th International Conference on Molecular Beam Epitaxy  2014/09
• Optimization of growth conditions of self-assembled InGaAs quantum dots suitable for spin injection  [Not invited]

  J. Takayama, T. Yamamura, X. Yang, T. Kiba, A. Subagyo, K. Sueoka, A. Murayama

  18th International Conference on Molecular Beam Epitaxy  2014/09
• Effects of spin density on the spin-tunneling dynamics from a quantum well into self-assembled quantum dots of InGaAs  [Not invited]

  T. Yamamura, T. Kiba, X. Yang, J. Takayama, A. Subagyo, K. Sueoka, A. Murayama

  18th International Conference on Molecular Beam Epitaxy  2014/09
• Electrical spin injection from Fe electrodes into InGaAs-based quantum structures  [Not invited]

  Y. Nomura, J. Takayama, T. Kiba, Y. Sasaki, T. Yamamura, X. Yang, A. Subagyo, K. Sueoka, A. Murayama

  18th International Conference on Molecular Beam Epitaxy  2014/09
• Quantum GaAs nanodisk light emitting diode fabricated by ultimate top-down neutral beam etching  [Not invited]

  Y. Tamura, C. Thomas, T. Kiba, Y. Wang, H. Sodabanlu, J. Takayama, M. Sugiyama, Y. Nakano, I. Yamashita, A. Murayama, S. Samukawa

  24th International Semiconductor Laser Conference  2014/09
• Electron g-factor and spin-relaxation in GaAs quantum disks fabricated by fully top-down lithography  [Not invited]

  T. Tanaka, T. Kiba, Y. Tamura, A. Higo, S. Samukawa, A. Murayama

  18th International Conference on Molecular Beam Epitaxy  2014/09
• Narrow line-width photoluminescence spectrum of GaAs nanodisks fabricated using bio-template ultimate top-down processes  [Not invited]

  Y. Tamura, A. Higo, T. Kiba, C. Thomas, Y. Wang, H. Sodabanlu, I. Yamashita, M. Sugiyama, Y. Nakano, A. Murayama, S. Samukawa

  14th IEEE International Conference on Nanotechnology  2014/08
• Fabrication of InGaAs quantum nanodisk array by using bio-template and top-down etching processes  [Not invited]

  K. Yoshikawa, A. Higo, C.Y. Lee, Y. Tamura, C. Thomas, T. Kiba, S. Ishii, H. Sodabanlu, Y. Wang, M. Sugiyama, Y. Nakano, I. Yamashita, A. Murayama, S. Samukawa

  14th IEEE International Conference on Nanotechnology  2014/08
• Fabrication of InGaAs quantum nanodisk by using Bio-template and neutral beam etching processes  [Not invited]

  K. Yoshikawa, A. Higo, C.Y. Lee, Y. Tamura, C. Thomas, T. Kiba, S. Ishii, H. Sodabanlu, Y. Wang, M. Sugiyama, Y. Nakano, I. Yamashita, A. Murayama, S. Samukawa

  6th IEEE International Nanoelectronics Conference  2014/07
• Optical characteristics of GaAs quantum nanodisks by the combination of bio-template ultimate top-down process  [Not invited]

  A. Higo, T. Kiba, Y. Tamura, S. Ishii, C. Thomas, T. Ozaki, A. Murayama, S. Samukawa

  6th IEEE International Nanoelectronics Conference  2014/07
• GaAs/AlGaAs quantum nanodisks by using neutral beam etching and their optical response  [Not invited]

  Y. Tamura, A. Higo, T. Kiba, C. Thomas, T. Okada, W. Yunpeng, H. Sodabanlu, M. Sugiyama, Y. Nakano, A. Murayama, S. Samukawa

  6th IEEE International Nanoelectronics Conference  2014/07
• New origins of lasing in ZnO; temperature dependence of modal gain contour map  [Not invited]

  C. Cho, A. Murayama, K. Kyhm

  6th IEEE International Nanoelectronics Conference  2014/07
• Quantum energy levels simulation for InGaAs/GaAs quantum nanodisks fabricated by ultimate top-down process  [Not invited]

  S. Ishii, A. Higo, K. Yoshikawa, Y. Tamura, T. Kiba, A. Murayama, Y. Li, S. Samukawa

  6th IEEE International Nanoelectronics Conference  2014/07
• Electrical spin injection in light-emitting diodes with InGaAs-based quantum structures  [Not invited]

  Y. Nomura, T. Kiba, J. Takayama, Y. Sasaki, T. Yamamura, A. Subagyo, K. Sueoka, A. Murayama

  6th IEEE International Nanoelectronics Conference  2014/07
• Effects of electric field on carrier and spin dynamics in InGaAs-based coupled quantum structures  [Not invited]

  J. Takayama, T. Kiba, T. Yamamura, Y. Nomura, A. Subagyo, K. Sueoka, A. Murayama

  6th IEEE International Nanoelectronics Conference  2014/07
• Ultrafast spin tunneling from a 2-dimesional electron system into self-assembled quantum dots of InGaAs  [Not invited]

  T. Yamamura, T. Kiba, X.J. Yang, J. Takayama, A. Subagyo, K. Sueoka, A. Murayama

  6th IEEE International Nanoelectronics Conference  2014/07
• Longitudinal and transvers electron-spin relaxation times in GaAs nanodisks fabricated by bio-nano templates and damage-free neutral-beam etching  [Not invited]

  T. Tanaka, T. Kiba, Y. Tamura, C. Thomas, A. Higo, S. Samukawa, A. Murayama

  6th IEEE International Nanoelectronics Conference  2014/07
• Ultrafast carrier capture in high optical quality GaAs nanodisks fabricated by bio-nano templates and damage-free neutral-beam etching  [Not invited]

  T. Kiba, A. Higo, Y. Tamura, C. Thomas, S. Samukawa, A. Murayama

  6th IEEE International Nanoelectronics Conference  2014/07
• Dynamics of photo-excited carriers and spin-related phenomena in III-V semiconductor nanostructures  [Invited]

  Akihiro Murayama

  IEEE 6th International Nanoelectronics Conference  2014/07
• GaAs/AlGaAs stacked layers etched by neutral beam for the fabrication of quantum dot structures  [Not invited]

  Y. Tamura, C. Thomas, A. Higo, T. Kiba, A. Murayama, S. Samukawa

  3rd International Symposium on Next-Generation Electronics  2014/05
• Full 3D quantum energy level simulation for GaAs/AlGaAs quantum nanodisks fabricated by ultimate top-down pocess  [Not invited]

  S. Ishii, A. Higo, Y. Tamura, T. Kiba, A. Murayama, Y. Li, S. Samukawa

  3rd International Symposium on Next-Generation Electronics  2014/05
• Optically probed electron-spin relaxation in GaAs nanostructures  [Not invited]

  T. Tanaka, T. Kiba, A. Murayama

  Seoul National University and Hokkaido University 2013 International Workshop on New Frontiers in Convergence Science and Technology  2013/12
• Dynamics pf photo-excited carriers in III-V semiconductor nanostructures  [Not invited]

  Akihiro Murayama

  Seoul National University and Hokkaido University 2013 International Workshop on New Frontiers in Convergence Science and Technology  2013/12
• The fabrication of GaAs quantum nanodisks combination of bio-template, neutral beam etching and MOVPE regrowth  [Not invited]

  A. Higo, Y.e Tamura, T. Kiba, C. Thomas, W. Yunpeng, M. Sugiyama, Y. Nakano, A. Murayama, S. Samukawa

  IEEE Nanotechnology Materials and Device Conference  2013/10
• Dynamics of photo-excited carriers and the spin states in III-V semiconductor nanostructures; application to quantum-dot lasing  [Invited]

  Akihiro Murayama

  3rd Annual World Congress of Nano Science and Technology  2013/09
• High density and high aspect ratio GaAs/AlGaAs nanopillar array fabricated by fusion of bio-template and neutral beam etching  [Not invited]

  Y. Tamura, A. Higo, T. Kiba, W. Yunpeng, C. Thomas, T. Okada, W. Hu, A. Murayama, M. Sugiyama, Y. Nakano, S. Samukawa

  2013 Internatinal Conference on Solid State Devices and Materials  2013/09
• Electron-spin dynamics in GaAs quantum wells coupled with II-VI diluted magnetic semiconductors  [Not invited]

  Akihiro Murayama

  NSF Workshop on US-Japan Frontiers in Novel Photonic-Magnetic Devices  2013/09
• Dynamics of exciton-spin relaxation in GaAs nanodisks fabricated by fully-top-down and damage-free lithography  [Not invited]

  T. Kiba, K. Suzaki, Y. Tamura, M. Igarashi, C. Thomas, W. Hu, T. Kaizu, Y. Okada, S. Samukawa, A. Murayama

  18th International Conference on Dynamical Processes in Excited States of Solids  2013/08
• Photoluminescence of high-density and sub-20-nm GaAs nanodisks fabricated with a neutral Beam etching process and MOVPE regrowth for high performance QDs devices  [Not invited]

  Y. Tamura, A. Higo, T. Kiba, W. Yunpeng, M. Igarashi, C. Thomas, W. Hu, M.E. Fauzi, A. Murayama, M. Sugiyama, Y. Nakano, S. Samukawa

  13th IEEE International Conference on Nanotechnology  2013/08
• Dynamics of optical spin injection in InGaAs self-assembled quantum dots with various growth conditions  [Not invited]

  T. Yamamura, X.J. Yang, T. Kiba, Y. Kuno, J. Takayama, A. Subagyo, K. Sueoka, A. Murayama

  18th International Conference on Dynamical Processes in Excited States of Solids  2013/08
• Transient Kerr effects in GaAs quantum disks fabricated by neutral-beam etching using bio-nano templates  [Not invited]

  T. Tanaka, T. Sasaki, T. Kiba, K. Kyhm, Y. Tamura, A. Higo, S. Samukawa, A. Murayama

  18th International Conference on Dynamical Processes in Excited States of Solids  2013/08
• Observation of optical gain in GaAs quantum disks fabricated by neutral-beam etching using bio-nano templates  [Not invited]

  K. Suzaki, T. Kiba, K. Kyhm, Y. Tamura, A. Higo, S. Samukawa, A. Murayama

  18th International Conference on Dynamical Processes in Excited States of Solids  2013/08
• Electroluminescence from excited states in InGaAs self-assembled quantum dots  [Not invited]

  Y. Sasaki, X.j. Yang, J. Takayama, T. Kiba, A. Subagyo, A. Ikeuchi, K. Sueoka, A. Murayama

  18th International Conference on Dynamical Processes in Excited States of Solids  2013/08
• Optical spin-injection dynamics at excited states in In0.5Ga0.5As quantum dots coupled with an In0.1Ga0.9As quantum well  [Not invited]

  X.J. Yang, T. Kiba, Y. Kuno, T. Yamamura, J. Takayama, A. Subagyo, K. Sueoka, A. Murayama

  18th International Conference on Dynamical Processes in Excited States of Solids  2013/08
• Dynamics of electron-spin injection in a heterovalent GaAs/AlGaAs/ZnMnSe structure with a coupled double quantum well of GaAs/AlGaAs  [Not invited]

  Y. Kuno, T. Sasaki, T. Kiba, V.Kh. Kaibyshev, F. Liaci, A.A. Toropov, S.V. Ivanov, Akihiro Murayama

  17th International Conference on Molecular Beam Epitaxy  2012/09
• High-density and sub-20-nm GaAs nanodisk array fabricated using neutral beam etching process for high performance QDs devices  [Not invited]

  Y. Tamura, M. Igarashi, M.E. Fauzi, R. Tsukamoto, T. Kaizu, T. Kiba, I. Yamashita, Y. Okada, A. Murayama, S. Samukawa

  12th International Conference on Nanotechnology  2012/08
• Picosecond carrier dynamics induced by coupling of wavefunctions in a Si-nanodisk array fabricated by neutral beam etching using bio-nano-templates  [Not invited]

  T. Kiba, Y. Mizushima, M. Igarashi, S. Samukawa, A. Murayama

  International Conference on Superlattices, Nanostructures, and Nanodevices  2012/07
• Plasmonic enhancement of photoluminescence in hybrid Si nanostructures with Au fabricated by fully top-down lithography  [Not invited]

  K. Nakaji, H. Lee, T. Kiba, M. Igarashi, S. Samukawa, A. Murayama

  International Conference on Superlattices, Nanostructures, and Nanodevices  2012/07
• Fabrication of Two-dimensional Array of Sub-10nm GaAs Nanodisk using Bio-template Neutral Beam Etching Process  [Not invited]

  S.H. Lin, M. Igarashi, X.Y. Wang, C.H. Huang, Y. Ohno, A. Murayama, S. Samukawa

  American Vacuum Society 58th International Symposium  2011/10
• High-density optical spin injection in self-assembled semiconductor quantum dots  [Not invited]

  A. Murayama, N. Tamura, T. Yamazaki, T. Kiba

  16th International Conference on Luminescence and Optical Spectroscopy of Condensed Matter  2011/06
• Inter-disk electron transfer in Si-nanodisk arrays fabricated by using bio-templates  [Not invited]

  T. Kiba, Y. Mizushima, A. Murayama, M. Igarashi, C.-H. Huang, S. Samukawa

  16th International Conference on Luminescence and Optical Spectroscopy of Condensed Matter  2011/06
• Damage-free top-down processes of fabricating two-dimensional array of sub-10nm nanometer GaAs nanodisks using bio-template and neutral beam etching for intermediate band solar cell applications  [Not invited]

  X.Y. Wang, C.H. Huang, R. Tsukamoto, T. Kaizu, M. Igarashi, P.A. Mortemousque, H. Shinohara, Y. Okada, A. Murayama, K. Itoh, Y. Ohno, I. Yamashita, S. Samukawa

  37th IEEE Photovoltaic Specialists Conference  2011/06
• Optical absorption, photoluminescence and miniband formation of a highly ordered and dense 2-dimensional array of Si nanodisks for quantum dot solar cells  [Not invited]

  M. Igarashi, C.H. Huang, X.Y. Wang, M.F. Budiman, Y. Tamura, T. Kiba, A. Murayama, T. Kaizu, Y. Okada, S. Samukawa

  37th IEEE Photovoltaic Specialists Conference  2010/06
• Surface/interface-related optical properties in Si nanodisks fabricated by neutral-beam etching using bio-templates  [Not invited]

  T. Kiba, K. Suzaki, H. Li, M. Igarashi, S. Samukawa, A. Murayama

  17th International Conference on Molecular Beam Epitaxy  2009/09
• Magnetic semiconductor nanostructures; toward spin manipulation in semiconductor quantum structures  [Invited]

  Akihiro Murayama

  International Workshop on Photons and Spins in Nanostructures  2009/07
• Carrier and spin injection from ZnMnSe to CdSe quantum dots  [Not invited]

  D.Dagnelund, I.A. Buyanova, T. Furuta, K. Hyomi, I. Suoma, A. Murayama, W.M. Chen

  3rd. International Conference on Quantum, Nano and Micro Technologies
• Spin dynamics in ZnO-based materials  [Not invited]

  W.M. Chen, I.A. Buyanova, T. Furuta, A. Murayama, D. P. Norton, S.J. Pearton, A. Osinsky, J. W. Dong

  5th International Conference on Physics and Applications of Spin-related Phenomena in Semiconductors
• Micro-photoluminescence study of electron-spin injection in self-assembled semiconductor quantum dots  [Not invited]

  K. Hyomi, M. Sakuma, A. Murayama

  15th International Conference on Luminescence and Optical Spectroscopy of Condensed Matter
• Transient magneto-photoluminescence in self-assembled quantum dots of a diluted magnetic semiconductor  [Not invited]

  S. Oshino, T. Furuta, I. Souma, A. Murayama, D. Dagnelund, I.A. Buyanova, W.M. Chen

  15th International Conference on Luminescence and Optical Spectroscopy of Condensed Matter
• Transfer dynamics of spin-polarized excitons into semiconductor quantum dots

  A. Murayama, T. Furuta, S. Oshino, K. Hyomi, M. Sakuma, I. Souma, D. Dagnelund, I.A. Buyanova, W.M. Chen

  15th International Conference on Luminescence and Optical Spectroscopy of Condensed Matter
• Cooling and spin-relaxation dynamics of spin-polarized excitons in a diluted magnetic semiconductor quantum well  [Not invited]

  A. Murayama, K. Saito, I. Souma

  8th International Conference on Excitonic Processes in Condensed Matter
• Propagation dynamics of exciton spins in a high-density semiconductor quantum dot system  [Not invited]

  A. Murayama, T. Furuta, S. Oshino, K. Hyomi, M. Sakuma, I. Souma, D. Dagnelund, I.A. Buyanova, W.M. Chen

  8th International Conference on Excitonic Processes in Condensed Matter
• Magneto-optical spectroscopy of spin injection from ZnMnSe to CdSe quantum dots  [Not invited]

  D. Dagnelund, I. A Buyanova, W.M. Chen, T. Furuta, K. Hyomi, I. Souma, A. Murayama

  The International Scanning Probe Microscopy Conference
• Spin injection and spin detection in semiconductor quantum structures  [Invited]

  W.M. Chen, I.A. Buyanova, A. Murayama, Y. Oka, S.J. Pearton, D. P. Norton, C.R. Abernathy, A. Osinsky, J. W. Dong

  The First Nordic Workshop on Spintronics and Nanomagnetism
• Magneto-optical properties and spin dynamics in novel II-VI and III-V semiconductor materials and nanostructures  [Invited]

  I.A. Buyanova, W.M. Chen, A. Murayama, Y. Oka, C.R. Abernathy, S.J. Pearton

  The Progress in Electromagnetics Research Symposium

Teaching Experience

Materials Science and EngineeringMaterials Science and Engineering School of Engineering, Hokkaido University
Exercise in Electrical and Electronic Engineering IExercise in Electrical and Electronic Engineering I School of Engineering, Hokkaido University
Integrated Material ProcessingIntegrated Material Processing Graduate School of Information Science and Technology, Hokkaido University
Integration Process EngineeringIntegration Process Engineering School of Engineering, Hokkaido University
Optical properties of semiconductor BOptical properties of semiconductor B Department of Applied Physics, Graduate School of Engineering, Tohoku University

Association Memberships

• 応用物理学会   

Research Projects

• 0-2Dハイブリッド半導体光電スピンインターフェース

  国立研究開発法人科学技術振興機構：先端的カーボンニュートラル技術開発（ALCA-Next）

  Date (from‐to) : 2023/11 -2027/03
• Semiconductor-based room temperature optical spintronics using novel spin-optical devices

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2023/04 -2026/03 

  Author : 村山 明宏
• Optical spin-functional transistor

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Challenging Research (Pioneering)

  Date (from‐to) : 2019/06 -2024/03 

  Author : 村山 明宏
• 半導体・酸化物複合ナノワイヤによる光・電子・スピン工学の融合

  日本学術振興会：科学研究費助成事業 基盤研究(A)

  Date (from‐to) : 2019/04 -2023/03 

  Author : 石川 史太郎, 村山 明宏, 長島 一樹
• Photoelectric conversion system of spin-information utilizing semiconductor quantum dots

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)

  Date (from‐to) : 2016/05 -2021/03 

  Author : 村山 明宏, 寒川 誠二, 末岡 和久

   

  低消費電力光デバイス実用材料であるIII-V 族化合物半導体量子ドットでは、電子のスピン緩和時間が発光寿命より十分長く、量子ドットに注入された電子のスピン状態は光電変換により発光の円偏光特性に変換される。そこで、室温動作可能な強磁性体電極から電子スピンを高効率に電流輸送するため、量子ドットへの超高速スピン注入および半導体バリア中のスピン輸送を研究し、量子ドットを用いた光電スピン情報変換システムの基盤を構築していく。交付申請書の研究計画に沿って得られた本年度の実績を以下にまとめる。 積層デバイス構造中の点状の量子ドットに対してスピン偏極電子を高速で捕獲し注入するため、二次元量子井戸に量子ドットを結合させた独自のスピン注入型エピタキシャル構造からなる光電スピン変換活性層の研究を推進した。まず、井戸ポテンシャルを介するドット間結合により励起状態のスピン偏強度を増幅し発光再結合中に維持した。また、ドットに注入された電子のエネルギー緩和過程を研究し、2種類の光学フォノン散乱が共鳴しスピン偏極が高く保たれるスピンフォノンボトルネックが存在することを示した。そこで電界効果素子を作製し、井戸とドットの次元性の異なるトンネルスピン結合に光学フォノンが共鳴散乱する極めて高効率のフォノン共鳴スピン注入を実現した。さらに、スピン注入に対する電界依存性を研究し、発光の円偏光特性すなわち注入電子スピンの偏極を電界で制御・反転できる素子を考案した。 半導体バリアのスピン輸送に関してはAlGaAs/GaAs超格子バリアの研究を進め、超格子の構造を最適化することによりスピン緩和を抑制した量子波による長距離スピン輸送が可能であることを示した。スピン緩和を抑えるスピン輸送チャネルや円偏光増幅を目指すバリアのナノ加工、金属強磁性体電極を用いるスピン注入型発光ダイオードの作製などの光機能スピン素子の研究も進めている。
• 二次元電子系と結合した量子ドットスピン状態の電界操作による動的スピン制御

  日本学術振興会：科学研究費助成事業 基盤研究(A)

  Date (from‐to) : 2016/04 -2019/03 

  Author : 村山 明宏
• Aharonov-Bohm effect in optically functional Type-I semiconductor quantum structures

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2015/04 -2017/03 

  Author : Murayama Akihiro

   

  We study the Aharonov-Bohm (AB) effect, that is an interference phenomenon caused by coherent phase difference of electron- and hole-wavefunctions, in Type-I semiconductor quantum dots (QDs) suitable for optical device applications. Optical detection of the AB effect has been limited to core-shell type-II QDs so far. Therefore, we aimed to obtain knowledge about the AB effect in the Type-I QDs by using quantum ring samples combining type-I GaAs QDs grown by droplet epitaxy, utilizing the one-dimensional nature of the wavefunctions in the ring direction. Magnetic-field dependences of the emission spectrum from a single quantum ring are measured by micro-photoluminescence spectroscopy under magnetic fields up to 5 T, and investigations are conducted in consideration of the Zeeman shift induced by the magnetic field.
• Spin-polarized Lasing in Quantum Dots

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)

  Date (from‐to) : 2010/04 -2015/03 

  Author : MURAYAMA Akihiro, SUEOKA Kazuhisa, SUGAWARA Hirotake

   

  We have studied spin-polarized lasing, which can transform electron-spin information into circular polarization properties in stimulated emission, by employing III-V compound semiconductor quantum dots (QDs) exhibiting strong suppression of spin relaxation. Spin-injection dynamics and spin relaxation in QDs in addition to fabrication processes of QDs have been studied for the purpose of temporal spin storage during the emission. We show that Pauli spin blocking is a major factor of spin loss during the spin injection into QDs. To resolve this issue, we conclude that high density QDs and tunneling of spins from two-dimensional electron systems realize highly efficient and ultrafast spin injection into QDs. QD light emitting diodes with active layers composed of QDs and metallic ferromagnetic spin electrodes have been fabricated, which indicates circularly polarized electroluminescence reflecting efficient electron-spin injection.
• Optically functional hybrid quantum dots

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2011 -2013 

  Author : MURAYAMA Akihiro

   

  Plasmonic effects induced by Au nano-particles in semiconductor quantum dots (QDs) were studied, aiming at efficient coupling between carriers in the QDs and lights. Various optically functional hybrid QDs with Au nano-particles were artificially fabricated, where the distance between the QD and the Au nano-particle was intentionally controlled by using modified molecular chains or nano-lithography techniques based on the protein engineering. In Si QDs, enhancements of the photoluminescence (PL) intensity originating from the localized plasmonic effect were observed. However, in II-VI or III-V QDs with high internal quantum efficiencies, PL intensities significantly decrease because of the energy transfer from the excited states in the QDs into the Au nano-particles, rather than the plasmonic enhancement effect.
• 半導体量子ドットネットワークにおけるスピン情報伝搬ダイナミクス

  日本学術振興会：科学研究費助成事業 挑戦的萌芽研究

  Date (from‐to) : 2008 -2010 

  Author : 村山 明宏

   

  研究実施計画にしたがい、平成21年に引き続き本年度は以下の研究を実施した。 (1)自己組織化量子ドットと希薄磁性半導体結合構造の微細加工 自己組織化量子ドットと希薄磁性半導体の結合構造を利用して、希薄磁性半導体に光生成した電子・励起子スピンを量子ドット集合体の特定位置に注入するため、電子ビームリソグラフィーにより希薄磁性半導体層の微細加工を行った。その結果、直径200nm程度のメサ構造を作製することができた。さらに、このような自己組織化量子ドットと希薄磁性半導体の結合ナノ構造に対して、磁場中での円偏光顕微発光分光を行い、特定の量子ドット集合体における高い円偏光度を持つ発光スペクトルを観測し、そのスピン注入現象を確認することができた。 (2)自己組織化量子ドットへのスピン注入と量子ドット間スピン伝搬ダイナミクスの分光計測 希薄磁性半導体と結合した量子ドットに対して、円偏光を用いたピコ秒時間分解発光分光により、量子ドットへのスピン注入を示す発光とその円偏光度の時間変化、およびその詳細な励起子エネルギー依存性や励起密度依存性、さらに温度依存性などを測定した。このような測定結果に対して、スピン伝搬ダイナミクスとドット内スピン緩和時定数を取り込んだレート方程式解析を行い、注入されたスピンのドット間伝搬ダイナミクスとドット内スピン緩和ダイナミクスについて明らかにした。その結果、低温領域において主としてトンネル過程によりスピン偏極キャリアが伝搬する場合、スピン緩和は量子ドット内におけるスピン緩和過程に支配される。これに対して、温度が上がってくると、各量子ドット内に局在しているスピンが熱励起されるためドット間を拡散し、このような拡散過程におけるスピン緩和が顕著となる。
• Fabrication of magnetic hybrid structures of semiconductor quantum dots and the spin-functional optical properties

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2007 -2009 

  Author : MURAYAMA Akihiro

   

  Magnetic hybrid structures of semiconductor quantum dots (QDs) with diluted magnetic semiconductors (DMSs), indicating giant magneto-optical properties, were fabricated. Spin-polarized electrons were optically generated in the DMS and were subsequently transferred into non-magnetic QDs via quantum tunneling (spin injection). The spin states of the electrons were temporally conserved in the QDs and were also read-out by circularly polarized photoluminescence.
• Optical Control of Electron Spins in Hybrid Quantum Structures of Diluted Magnetic Semiconductors

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2005 -2006 

  Author : OKA Yasuo, MURAYAMA Akihiro

   

  The objective of the research program is following: 1.Designing and fabrication of new hybrid nanostructures composed of II-VI compound diluted magnetic semiconductors and magnetic metals. 2.Study of optical spin injection and spin relaxation in the hybrid nanostructures of quantum dots and quantum wells for the application on spin electronic devices. We have fabricated, for the above objectives, the quantum structures and hybrid nanostructures with CdTe,CdSe,ZnTe,ZnSe and magnetic materials of Mn and Co by using molecular expitaxy and electron beam lithography. Fabricated quantum nanostructures are studied by femtosecond laser spectroscopy by applying high magnetic fields. Spin injection processes of electrons, holes and excitons are investigated in the quantum wells and quantum dots of ZnMnSe-ZnSe,CdMnSe-CdSe and CdMnTe-CdTe systems. Transient photoluminescence of excitons shows fast spin injection and spin relaxation processes in the quantum structures induced by the magnetic field. Ultrafast spin dynamics of carriers is investigated in the diluted magnetic double quantum wells by transient pump-probe spectroscopy. The spin injection dynamics of electrons and holes are clarified in femtosecond time domain. Hybrid nanostructures with the diluted magnetic semiconductors and the magnetic metals were fabricated by electron beam lithography technique. The diluted magnetic quantum disks in the hybrid structures show the Zeeman splitting without applying external magnetic field, which verifies the affection the ferromagnetic nano-scale magnets neighboring to the quantum disks. The obtained results in the present research have high possibilities for spin electronic applications.
• 磁性体・半導体ハイブリッド構造によるナノスピンの生成と制御

  日本学術振興会：科学研究費助成事業 特定領域研究

  Date (from‐to) : 2004 -2005 

  Author : 村山 明宏, 岡 泰夫, 西林 一彦

   

  本研究においては、化合物磁性半導体の原子層制御エピタキシャル量子井戸・規則配列量子ドット・自己組織化量子ドット等の各種ナノ量子構造を作製する。また、Co系合金などの金属強磁性体、あるいは半導体結晶とエピタキシャル成長するMn系化合物磁性体を接合あるいは組み合わせた、新しい磁性体・半導体ハイブリッドナノ構造を創出する。そして、このような磁性体・半導体ハイブリッドナノ構造のスピン光物性を調べるとともに、半導体のスピン秩序を磁性体により制御することを試みる。 特に本年度は、これまでの研究成果である磁性半導体と非磁性半導体のナノ構造作成技術を生かして、非磁性半導体CdSe自己組織化量子ドットと磁性半導体ZnCdMnSe量子井戸をトンネル結合させた全く新しい光スピン機能性量子ナノ構造を創製した。その結果、磁性半導体において光生成したスピン偏極電子を、共鳴トンネル効果により超高速かつ高効率に自己組織化量子ドットに注入することに成功した。 さらに、電子ビームリソグラフィーにより作製した垂直磁化Co/Pt多層膜と磁性半導体ZnCdMnSe量子井戸の複合ナノディスク構造を考案・作製した。ZnCdMnSeナノディスクの励起子発光の円偏光特性を調べ、Co垂直磁化より半導体ナノディスクに生じる局所的な垂直磁場により誘導される励起子巨大ゼーマン効果の発現を明らかにした。すなわち、強磁性体ナノ構造から生じる磁場を利用して、半導体励起子キャリアのスピン状態を制御することに成功した。 また、磁場中円偏光ポンププローブ分光により、磁性半導体CdMgMnTeと非磁性半導体CdTe量子井戸をトンネル結合させた磁性結合二重量子井戸におけるキャリアスピンダイナミクスを研究した。その結果、磁性井戸において光生成したスピン偏極電子・正孔は、個別トンネルにより非磁性井戸へ輸送されることを示した。
• Magnetic properties and optical spin functionalities of atomically layer-controlled hybrid structures of semiconductors with magnetic materials

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2003 -2005 

  Author : MURAYAMA Akihiro, NISHIBAYASHI Kazuhiro

   

  In this research, atomically layer-controlled hybrid structures of semiconductors with magnetic materials are fabricated. It has aimed to research microscopic magnetic interactions at the interfaces and magneto-optical functionalities in these nanostructures, and to develop hybrid nano-materials exhibiting new optical spin functionalities. The following results are obtained. (1) ZnCdSe quantum wells were epitaxially grown with magnetic delta-doping of antiferromagnetic MnSe atomic layers. The magnetic spins of such an atomically layer-controlled ultra-thin film were studied and the correlation with excitons was clarified. (2) Hybrid nanostructures of ZnCdMnSe quantum wells with Co wires were developed by electron-beam lithography. Light scattering were observed due to the ferromagnetic spin waves in Co and the spin flip of the Mn ion. As a result, the local effective magnetic-field-distribution from the Co was quantified in such a magnetic hybrid nanostructure. (3) Magnetic asymmetric double quantum wells were fabricated, where non-magnetic semiconductor ZnCdSe and magnetic semiconductor ZnCdMnSe quantum wells were coupled, and the excitonic spin dynamics was studied by circularly polarized time-resolved PL in magnetic fields. It was observed that the type-II transition was induced by the magnetic field depending on the spin. This realizes a new optical spin functionality to separate spatially the hole spins. (4) Hybrid nano-disk structures of magnetic semiconductor ZnCdMnSe quantum wells with perpendicular magnetic Co/Pt multilayers were newly developed by an electron-beam lithography technique. It succeeded in the control of excitonic spin state in the semiconductor nano-disks by the local perpendicular magnetic fields generated from the perpendicular Co magnetization. (5) A optical spin functionality was developed in hybrid quantum nanostructures of CdSe Self-assembled quantum dots with magnetic semiconductor ZnCdMnSe quantum wells with tunnel barriers.
• Optical Spin Injection and Carrier Transport in Hybrid Nanostructures of Semiconductors and Magnetic Metals

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2001 -2003 

  Author : OKA Yasuo, NISHIBAYASHI Kazuhiro, TOMITA Takuro, MURAYAMA Akihiro

   

  The objective of the research is following: 1.Fabrication of hybrid nanostrctures of quantum wires, quantum dots and quantum wells, which are composed of II-VI compound diluted magnetic semiconductors and magnetic metals. 2.Study of optical spin injection and spin transport in the hybrid nanostructures and application for spin electronic devices. For the above objective, we have fabricated the quantum nanostructures and hybrid nanostructures with CdTe, CdSe, ZnTe, ZuSe and magnetic materials of Mn and Co by using molecular expitaxy and electron beam lithography methods. Fabricated quantum and hybrid nanostructures are studied by femtosecond laser spectroscopy in high magnetic fields. Spin injection processes are investigated in CdTe-CdMnTe double quantum wells, where the transient photoluminescence of quantum-well excitons shows that spin injection and spin relaxation processes. Spin switching processes are clarified in ZnTe-ZnMnTe spin superlattices, where the distribution of up-and down-spin states of excitons is spatially separated in Zute and ZnMnTe layers by the external magnetic fields. The lowest spin state of excitons is modified from that of the ZnTe layer to that of the ZuMnTe due to the large Zeeman splitting of the exciton spins in the ZnMnTe layer. From the transient characteristics of the exciton photoluminescence, the reverse spin injection process (spin switching) is confirmed and the spin injection times are determined. Ultrafast spin dynamics of excitons is investigated in these diluted magnetic nanostructures by transient pump-probe spectroscopy. The spin dynamics in the high density electron-hole plasma, excitons, and Mn ions are clarified in the femotsecond to nanosecond time region. Fabrication of hybrid nanostructures is made by using electron beam lithography technique. The diluted magnetic quantum wells in the hybrid structures are affected by the magnetic field, which is induced by the ferromagnetic Co wires neighboring to the quantum wells. These phenomena have high possibilities for spin electronic applications.
• Fabrication and Study of Nanostructure Diluted Magnetic Semiconductors

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

  Date (from‐to) : 1996 -1998 

  Author : OKA Yasuo, MURAYAMA Akihiro, TAKAHASI Masaaki, YANATA Kohei, SHEN J.X.

   

  The objective of this research project is to fabricate new nanostructure lattices composed of diluted magnetic semiconductors (DMSs) and also to study magneto-optical properties of the nanostructures. For this purposes, we have fabricated 2-dimensional quantum wells, 1-dimensional quantum wires, and 0-dimensional quantum dots by molecular beam epitaxy, atomic beam epitaxy, and electron-beam lithography techniques. Materials we have fabricated are Cd_<1-x>Mn_xTe and Cd_<1-x>Mn_xSe with Mn concentration of x= 0.03-0.3. Obtained these nanostructures have been studied by the ultrafast laser spectroscopy using femto-second pulse lasers. Time resolved photoluminescence has been measured in Cd_<1-x>Mn_xTe quantum wells by the selective excitation of the quantum-well exciton states. The transient behavior of the exciton luminescence clearly shows the formation process of the excitonic magnetic polarons, which is suppressed by the strong external magnetic fields. Quantum dots of Cd_<1-x>Mn_xSe grown by the Stranski-Krastanow mode on ZnSe buffer layers show very fast decay of the excitons in the dots. The lifetime of the quantum dot excitons is markedly increased by the external magnetic fields. The phenomena are interpreted by decrease of the nonradiative process due to the shrinkage of the exciton wavefunction by the magnetic field. Pump-probe transient absorption spectroscopy has been made on Cd_<1-x>Mn_xTe quantum well, The exciton and magnetic polaron dynamics are observed in the 2 ps to 3 ns time region. Quantum wires of Zn_<1-x>Cd_xSe system show the photoluminescence evidence of the 1-dimensional confinement effect as well as the relaxation of the lattice strains by decreasing the wire width. Fabrication of Cd_<1-x>Mn_xSe quantum wires is under progress. The remarkable magneto-optical effects of the nanaostructure DMSs elucidated in the present project will stimulate the research of the new magneto-optical microdevices.