基本情報

所属

• 電子科学研究所　物質科学研究部門

職名

• 准教授

学位

• 博士（工学）

ホームページURL

http://qed4.es.hokudai.ac.jp/kondo.htm
http://qed4.es.hokudai.ac.jp/en/kondo.htm

科研費研究者番号

• 50360946

J-Global ID

• 200901088442062350

研究キーワード

• 磁性   電子構造論   輸送理論   スピントロニクス   多体問題   Many Particle Problem   

研究分野

• ナノテク・材料 / 結晶工学
• ナノテク・材料 / 応用物性
• 自然科学一般 / 磁性、超伝導、強相関系

担当教育組織

•  修士課程　理学院
•  博士課程　理学院

所属学協会

• Material Research Society   日本応用物理学会   日本磁気学会   日本物理学会   

研究活動情報

論文

• General formula of chiral anomaly for type-I and type-II Weyl semimetals

  K. Morishima, K. Kondo

  Applied Physics Letters 119 13 131907-1 - 131907-6 2021年09月29日 [査読有り]
  
• A comparison of magnetoconductivities between type-I and type-II Weyl semimetals

  森島 一輝, 近藤 憲治

  Journal of Applied Physics 129 12 125104 - 125104 2021年03月28日 [査読有り][通常論文]
  
• A proposal of strong and weak phases in second-order topological insulators

  小森至瑠, 近藤憲治

  Journal of Physics Communications 4 12 125005-1 - 125005-12 IOP Publishing 2020年12月14日 [査読有り][通常論文]
   

  Accepted Manuscript
• Theoretical comparison between skyrmion and skyrmionium motions for spintronics applications

  石田雄一, 近藤 憲治

  Japanese Journal of Applied Physics 59 SGGI04-1 - SGGI04-7 2020年02月20日 [査読有り][通常論文]
  
• Application of Singularity Theory to Bifurcation of Band Structures in Crystals

  H. Teramoto, A. Tsuchida, K. Kondo, S. Izumiya, M. Toda, T. Komatsuzaki

  Journal of Singularities 21 289 - 302 2020年01月 [査読有り][通常論文]
  
• An Effect of the Gilbert Damping Constant on the Skyrmion Hall effect

  石田雄一, 近藤 憲治

  Journal of Magnetism and Magnetic Materials, 493 1 165687-1 - 165687-7 2020年01月 [査読有り][通常論文]
  
• Quantum spin Hall phase in honeycomb nanoribbons with two different atoms: edge shape effect to bulk-edge correspondence

  近藤 憲治, 伊藤 蓮

  J. Phys. Commun. 3 055007-1 - 055007-12 2019年05月 [査読有り][通常論文]
  
• Origin of biquadratic interlayer exchange coupling in Co2MnSi-based currentperpendicular- to-plane pseudo spin valves

  M. Inoue, K. Inubushi, D. Mouri, T. Tanimoto, K. Nakada, K. Kondo, M. Yamamoto, T. Uemura

  Appl. Phys. Lett. 114 062401-1 - 062401-5 2019年02月 [査読有り][通常論文]
  
• Symmetric and asymmetric wave-guides for multi-striped orthogonal photon-photocarrier-propagation solar cells (MOP3SC)

  Akira Ishibashi, Hikaru Kobayashi, Nobuo Sawamura, Kenji Kondo, Tsuyoshi Kasai

  Proceedings of the 2017 IEEE International Conference on Applied System Innovation: Applied System Innovation for Modern Technology, ICASI 2017 1477 - 1479 2017年07月21日 [査読有り][通常論文]
   

  Waveguide-coupled orthogonal photon-photocarrier propagation solar cell (MOP3SC) in which the photons propagate in the direction orthogonal to that of the photocarriers'is of potential interest for a high efficiency solar cell. We have studied feasibility of symmetric waveguides for MOP3SC. The symmetric waveguide with refractive index modulation structure would not give a very high efficiency due to the reason originated from the spatial and time-reversal symmetries. To overcome the problem, we propose an asymmetric redirection waveguide consisting of periodic parabola mirrors.
• Classification of Hamiltonians in neighborhoods of band crossings in terms of the theory of singularities

  Hiroshi Teramoto, Kenji Kondo, Shyuichi Izumiya, Mikito Toda, Tamiki Komatsuzaki

  JOURNAL OF MATHEMATICAL PHYSICS 58 7 073502-1 - 073502-39 2017年07月 [査読有り][通常論文]
   

  We classify two-by-two traceless Hamiltonians depending smoothly on a threedimensional Bloch wavenumber and having a band crossing at the origin of the wavenumber space. Recently these Hamiltonians attract much interest among researchers in the condensed matter field since they are found to be effective Hamiltonians describing the band structure of the exotic materials such as Weyl semimetals. In this classification, we regard two such Hamiltonians as equivalent if there are appropriate special unitary transformation of degree 2 and diffeomorphism in the wavenumber space fixing the origin such that one of the Hamiltonians transforms to the other. Based on the equivalence relation, we obtain a complete list of classes up to codimension 7. For each Hamiltonian in the list, we calculate multiplicity and Chern number [D. J. Thouless et al., Phys. Rev. Lett. 49, 405 (1982); M.V. Berry, Proc. R. Soc. A 392, 45 (1983); and B. Simon, Phys. Rev. Lett. 51, 2167 (1983)], which are invariant under an arbitrary smooth deformation of the Hamiltonian. We also construct a universal unfolding for each Hamiltonian and demonstrate how they can be used for bifurcation analysis of band crossings. Published by AIP Publishing.
• Optical Simulation for Multi-Striped Orthogonal Photon-Photocarrier-Propagation Solar Cell (MOP3SC) with Redirection Waveguide

  Akira Ishibashi, H. Kobayashi, T. Taniguchi, K. Kondo, T. Kasai

  3D Research 7 4 33 1 - 5 2016年12月01日 [査読有り][通常論文]
   

  We have calculated optical fields for waveguide-coupled orthogonal photon-photocarrier propagation solar cell (MOP3SC)in which the photons propagate in the direction orthogonal to that of the photocarriers’. By exploiting the degree of freedom along the photon propagation and using multi-semiconductor stripes in which the incoming photons first encounter the widest gap semiconductor, and the narrowest at last, we can convert virtually the whole spectrum of solar spectrum into electricity resulting in high conversion efficiency. The waveguide-coupled MOP3SC can not only optimize the absorption of light and the photocarrier collection independently converting virtually the whole spectrum of sunlight into electricity, but also can serve as a highly efficient concentration solar-cell system with low temperature rise thanks to its minimal thermal dissipation and the diffusive-light-convertibility when used with the parabola cross-section structure on top of the waveguide. The waveguide-coupled MOP3SC is also of potential interest as a high reliability system, because the high energy photons that can damage bonding of the materials, being converted into electricity already at upstream, never go into the medium or narrow gap semiconductors, resulting in low degradation of materials used in the MOP3SC.
• A Derivation of Aharonov-Casher Phase and Another Adiabatic Approximation for Pure Gauge under General Rashba Effects

  Kenji Kondo

  SPIN, World Scientifc Publishing 2016年10月 [査読有り][招待有り]
  
• Transient analysis of oblique Hanle signals observed in GaAs

  Zhichao Lin, Kenji Kondo, Masafumi Yamamoto, Tetsuya Uemura

  JAPANESE JOURNAL OF APPLIED PHYSICS 55 4 04EN03  2016年04月 [査読有り][通常論文]
   

  A transient response of nuclear spins in GaAs to a change in a magnetic field was analyzed based on the time evolution of nuclear spin temperature. Simulation results well reproduced our experimental results on transient oblique Hanle signals observed in an all-electrical spin injection device, enabling a quantitative understanding of nuclear spin dynamics in the presence of a hyperfine interaction between nuclei and polarized electrons. Analysis regarding the time evolution of nuclear spin temperature revealed that the hysteretic nature of a nuclear field with respect to the sweep direction of an external field was caused by the delay of time response of nuclear spin temperature to a change in the magnetic field. This analysis provides a deep understanding of nuclear spin dynamics in semiconductors. (C) 2016 The Japan Society of Applied Physics
• Edge-Illumination Scheme for Multi-striped Orthogonal Photon-Photocarrier- Propagation Solar Cells

  A. Ishibashi, S. White, N. Kawaguchi, K. Kondo, T. Kasai

  Int. J. Eng. Tech. Res. 6 1 115 - 117 2016年 [査読有り][通常論文]
  
• Spin filter effects in an Aharonov–Bohm ring with double quantum dots under general Rashba spin–orbit interactions

  Kenji Kondo

  New Journal of Physics 18 013002  2015年12月 [査読有り][通常論文]
   

  Many researchers have reported on spin filters using linear Rashba spin-orbit interactions (SOI). However, spin filters using square and cubic Rashba SOIs have not yet been reported. We consider that this is because the. Aharonov-Casher (AC) phases acquired under square and cubic Rashba SOIs are ambiguous. In this study, we try to derive the AC phases acquired under square and cubic Rashba SOIs from the viewpoint of non-Abelian SU(2) gauge theory. These AC phases can be derived successfully from the non-Abelian SU(2) gauge theory without the completing square methods. Using the results, we investigate the spin filtering in a double quantum dot (QD) Aharonov-Bohm (AB) ring under linear, square, and cubic Rashba SOIs. This AB ring consists of elongated QDs and quasi-one-dimensional quantum nanowires under an external magnetic field. The spin transport is investigated from the left nanowire to the right nanowire in the above structure within the tight-binding approximation. In particular, we focus on the difference of spin filtering among linear, square, and cubic Rashba SOIs. The calculation is performed for the spin polarization by changing the penetrating magnetic flux for the AB ring subject to linear, square, and cubic Rashba SOIs. It is found that perfect spin filtering is achieved for all of the Rashba SOIs. This result indicates that this AB ring under general Rashba SOIs can be a promising device for spin current generation. Moreover, the AB rings under general Rashba SOIs behave in totally different ways in response to penetrating magnetic flux, which is attributed to linear, square, and cubic behaviors in the in-plane momentum. This result enables us to make a clear distinction between linear, square, and cubic Rashba SOIs according to the peak position of the perfect spin filtering.
• Validity of the free electron model for two-dimensional electrodes

  Kenji Kondo

  Materials Research Society Symposium Proceedings 1753 60 - 65 2015年 [査読有り][通常論文]
   

  Generally, the electrodes are regarded as free electron gases when we calculate the transport characteristics of nanostructure materials or devices. In three dimensional electrodes, there are little electron correlation. However, in low-dimensional electrodes, electron correlation becomes much larger than that in three dimensional ones. Recently, nanotechnology has made much progress to fabricate two-dimensional (2D) electrodes easily and precisely. As a result, we must consider whether two-dimensional electrodes can be regarded as free electron gases. In this study, we investigate the electron energy spectrum of 2D electrodes, taking into consideration the electron correlation These results suggest that the free electron model is justified only at the Fermi momentum and that we should not regard 2D electrodes as free electron gases without careful consideration under high electric field and/or high temperature.
• Magnetic Properties on FeAl Stripes and Dots Induced by Nanosecond Pulsed Laser Irradiation

  H. Kaiju, Y. Yoshida, S. Watanabe, Kenji Kondo, A. Ishibashi, K. Yoshimi

  J. Magn. Soc. Jpn. 38 157 - 161 2014年07月 [査読有り][通常論文]
  
• Spin transport in normal metal/insulator/topological insulator coupled to ferromagnetic insulator structures

  Kenji Kondo

  JOURNAL OF APPLIED PHYSICS 115 17 17C701-1 - 17C701-3 2014年05月 [査読有り][通常論文]
   

  In this study, we investigate the spin transport in normal metal (NM)/insulator (I)/topological insulator (TI) coupled to ferromagnetic insulator (FI) structures. In particular, we focus on the barrier thickness dependence of the spin transport inside the bulk gap of the TI with FI. The TI with FI is described by two-dimensional (2D) Dirac Hamiltonian. The energy profile of the insulator is assumed to be a square with barrier height V and thickness d along the transport-direction. This structure behaves as a tunnel device for 2D Dirac electrons. The calculation is performed for the spin conductance with changing the barrier thickness and the components of magnetization of FI layer. It is found that the spin conductance decreases with increasing the barrier thickness. Also, the spin conductance is strongly dependent on the polar angle h, which is defined as the angle between the axis normal to the FI and the magnetization of FI layer. These results indicate that the structures are promising candidates for novel tunneling magnetoresistance devices. (C) 2014 AIP Publishing LLC.
• Magnetic properties on the surface of FeAl stripes induced by nanosecond pulsed laser irradiation

  H. Kaiju, Y. Yoshida, S. Watanabe, K. Kondo, A. Ishibashi, K. Yoshimi

  JOURNAL OF APPLIED PHYSICS 115 17 17B901-1 - 17B901-3 2014年05月 [査読有り][通常論文]
   

  We demonstrate the formation of magnetic nanostripes on the surface of Fe52Al48 induced by nanosecond pulsed laser irradiation and investigate their magnetic properties. The magnetic stripe consists of a disordered A2 phase of Fe-Al alloys with Al-oxide along the [110] direction on the (111)-oriented plane. According to the focused magneto-optical Kerr effect measurement, the coercive force of the magnetic stripe obeys the 1/cos theta law, where theta is the field rotation angle estimated from the stripe direction. Also, the jump field can be observed in the magnetic hysteresis loop. These results indicate that the magnetization reversal in the magnetic stripe originates from the domain pinning, showing that the magnetization rotates incoherently. (C) 2014 AIP Publishing LLC.
• Nanopatterns induced by pulsed laser irradiation on the surface of an Fe-Al alloy and their magnetic properties

  Yutaka Yoshida, Kazuya Oosawa, Seiichi Watanabe, Hideo Kaiju, Kenji Kondo, Akira Ishibashi, Kyosuke Yoshimi

  APPLIED PHYSICS LETTERS 102 18 183109-1 - 183109 -4 2013年05月 [査読有り][通常論文]
   

  We have studied nanopatterns induced by nanosecond pulsed laser irradiation on (111) plane surfaces of a polycrystalline iron-aluminum alloy and evaluated their magnetic properties. Multiple nanosecond pulsed laser irradiation induces a wavelength-dependent surface transformation of the lattice structure from a B2-type to a supersaturated body centered cubic lattice. The selective formation of surface nanopatterns consisting of holes, stripes, polygonal networks, and dot-like nanoprotrusions can be observed. Furthermore, focused magneto-optical Kerr effect measurements reveal that the magnetic properties of the resultant nanostructured region changes from a paramagnetic to a ferromagnetic phase in accordance with the number of laser pulses. (C) 2013 AIP Publishing LLC.
• Focused Magneto-Optic Kerr Effect Spectroscopy in Ni75Fe25 and Fe Ferromagnetic Thin Films on Organic Substrates

  Kenji Kondo, Hideo Kaiju, Akira Ishibashi

  JAPANESE JOURNAL OF APPLIED PHYSICS 52 1 013001-1 - 013001-5 2013年01月 [査読有り][通常論文]
   

  We apply the theory of the magneto-optic Kerr effect (MOKE) for multilayer thin films to analyze the surface magnetic properties, which have been observed using focused MOKE, for Ni75Fe25 and Fe thin films evaporated on poly(ethylene naphthalate) (PEN) organic substrates. The calculation is performed for the thickness dependence and incident angle dependence of Kerr rotation and ellipticity. We have measured the thickness dependence of Kerr rotation at a wavelength of 405nm for both Ni75Fe25 and Fe thin films on PEN organic substrates. These results are fitted using the theory by adjusting the values of magneto-optic constants Q's. These Q's are 0.01 exp(-i48 pi/180) and 0.025 exp(-i47 pi/180) for Ni75Fe25 and Fe thin films, respectively. These results lead to the quantitative estimation of the surface magnetic properties of thin films on organic substrates. Also, the magneto-optic constants are estimated for ferromagnetic thin films on organic substrates for the first time. (C) 2013 The Japan Society of Applied Physics
• Critical effect of spin-dependent transport in a tunnel barrier on enhanced Hanle-type signals observed in three-terminal geometry

  Tetsuya Uemura, Kenji Kondo, Jun Fujisawa, Ken-ichi Matsuda, Masafumi Yamamoto

  APPLIED PHYSICS LETTERS 101 13 132411-1 - 132411-4 2012年09月 [査読有り][通常論文]
   

  The MgO thickness dependence of Hanle signals in Co50Fe50/MgO/n-Si tunnel junctions was investigated using a three-terminal geometry. The observed Hanle signal is several orders of magnitude stronger than the predicted value by conventional theory as reported in many literatures. Furthermore, the magnitude of the spin signal depends on the junction resistance rather than the channel resistance, implying that the largest part of the observed Hanle signal is not caused by spin accumulation in the semiconductor region. A possible origin of the observed strong Hanle signal is due to a modulation of the tunneling resistance by a magnetic field, which is induced by the spin precession in localized states formed in the vicinity of the Co50Fe50/MgO interface. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754545]
• Tunnel barrier thickness dependence of Hanle-type signals in CoFe/MgO/n-Si and CoFe/MgO/n-Ge junctions investigated through three-terminal configuration

  T. Uemura, G.-f. Li, J. Fujisawa, K. Kondo, K.-i. Matsuda, M. Yamamoto

  2012 Int'l Conference on Solid State Devices and Materials (SSDM 2012), Extended Abstracts (USB memory) 1223 - 1224 2012年09月 [査読有り][通常論文]
  
• Spin transport in ferromagnet/semiconductor/ferromagnet structures with cubic Dresselhaus spin-orbit-interaction

  Kenji Kondo

  JOURNAL OF APPLIED PHYSICS 111 7 07C713-1 - 07C713-3 2012年04月 [査読有り][通常論文]
   

  We have investigated the spin transport in ferromagnet (FM)/semiconductor (SC)/ferromagnet (FM) structures with a central SC barrier region exhibiting cubic Dresselhaus spin-orbit-interaction (SOI). The energy profile of the barrier is assumed to be a square with height V and thickness d along z-direction. The magnetoresistance (MR) ratio has been calculated for three different barriers, GaAs, GaSb, and GaAs without SOI as a function of barrier thickness. We have found that the MR ratio has a negative value for GaAs barrier with SOI except for very thin barrier thickness. In the case of GaSb barrier, the MR ratio changes sign from negative to positive with increasing the barrier thickness. Also, we have calculated the MR ratio with changing the spin coupling constant. (C) 2012 American Institute of Physics. [doi:10.1063/1.3677799]
• Longitudinal and transverse exciton-spin relaxation in a single InAsP quantum dot embedded inside a standing InP nanowire using photoluminescence spectroscopy

  H. Sasakura, C. Hermannstädter, S. N. Dorenbos, N. Akopian, M. P. Van Kouwen, J. Motohisa, Y. Kobayashi, H. Kumano, K. Kondo, K. Tomioka, T. Fukui, I. Suemune, V. Zwiller

  Physical Review B - Condensed Matter and Materials Physics 85 7 2012年02月29日 [査読有り][通常論文]
   

  We have investigated the optical properties of a single InAsP quantum dot embedded in a standing InP nanowire. Elongation of the transverse exciton-spin relaxation time of the exciton state with decreasing excitation power was observed by first-order photon correlation measurements. This behavior is well explained by the motional narrowing mechanism induced by Gaussian fluctuations of environmental charges in the nanowire. The longitudinal exciton-spin relaxation time is evaluated by the degree of the random polarization of emission originating from exciton states confined in a single-nanowire quantum dot by using Mueller calculus based on Stokes parameters representation. The reduction in the random polarization component with decreasing excitation power is caused by suppression of the exchange interaction of electron and hole due to an optically induced internal electric field by the dipoles at the wurtzite and zinc-blende heterointerfaces in the InP nanowire. © 2012 American Physical Society.
• Longitudinal and transverse exciton-spin relaxation in a single InAsP quantum dot embedded inside a standing InP nanowire using photoluminescence spectroscopy

  H. Sasakura, C. Hermannstaedter, S. N. Dorenbos, N. Akopian, M. P. van Kouwen, J. Motohisa, Y. Kobayashi, H. Kumano, K. Kondo, K. Tomioka, T. Fukui, I. Suemune, V. Zwiller

  PHYSICAL REVIEW B 85 7 075324-1 - 075324-7 2012年02月 [査読有り][通常論文]
   

  We have investigated the optical properties of a single InAsP quantum dot embedded in a standing InP nanowire. Elongation of the transverse exciton-spin relaxation time of the exciton state with decreasing excitation power was observed by first-order photon correlation measurements. This behavior is well explained by the motional narrowing mechanism induced by Gaussian fluctuations of environmental charges in the nanowire. The longitudinal exciton-spin relaxation time is evaluated by the degree of the random polarization of emission originating from exciton states confined in a single-nanowire quantum dot by using Mueller calculus based on Stokes parameters representation. The reduction in the random polarization component with decreasing excitation power is caused by suppression of the exchange interaction of electron and hole due to an optically induced internal electric field by the dipoles at the wurtzite and zinc-blende heterointerfaces in the InP nanowire.
• Surface roughness and magnetic properties of co ferromagnetic thin films on polyethylene naphthalate organic substrates

  Hideo Kaiju, Taro Abe, Kenji Kondo, Akira Ishibashi

  Journal of the Vacuum Society of Japan 55 4 187 - 190 2012年 [査読有り][通常論文]
   

  We have investigated surface roughnesses and magnetic properties of Co ferromagnetic thin films evaporated on polyethylene naphtalate (PEN) organic substrates. As a result, the surface roughness decreases from 1.3 to 0.55 nm with increasing the Co thickness up to 55 nm, where a two-step smoothing phenomenon can be seen. As for magnetic properties, the coercive force and the squareness of the hysteresis loop show the maximum values at a Co thickness of 5.3 nm. This experimental result can be explained by the competition between the shape magnetic anisotropy and the induced magnetic anisotropy of Co ferromagnetic thin films. Copyright © 2002 - 2012 Hogrefe Publishing.
• Large thermoelectric voltage in point contacts of Ni ferromagnetic metals

  Kenji Kondo, Hideo Kaiju, Akira Ishibashi

  Materials Research Society Symposium Proceedings 1314 7 - 12 2011年 [査読有り][通常論文]
   

  Recently, we have proposed a spin quantum cross structure (SQCS) device toward the realization of novel spintronics devices. In this paper, we have investigated thermoelectric effects in point contacts (PCs) of Ni ferromagnetic metals using SQCS devices, theoretically and experimentally. The calculated results show that the thermoelectric voltage V q changes from 0.48 mV to 2.12 mV with the temperature difference of PCs increasing from 10 K to 50 K. Also, the magnitude of the theoretical thermoelectric voltage agrees very well with that of the experimental result. PCs of SQCS devices with Ni electrodes can serve as spin dependent thermobatteries. © 2011 Materials Research Society.
• Surface and interface structures and magnetic properties of Ni and Ni 75Fe25 thin films on polyethylene naphthalate Organic Substrates

  Hideo Kaiju, Nubla Basheer, Taro Abe, Kenji Kondo, Akihiko Hirata, Manabu Ishimaru, Yoshihiko Hirotsu, Akira Ishibashi

  Journal of the Vacuum Society of Japan 54 3 203 - 206 2011年 [査読有り][通常論文]
   

  We have investigated structural and magnetic properties of Ni and Ni 75Fe25 thin films evaporated on polyethylene naphtalate (PEN) organic substrates, which can be expected as electrodes of our proposed nanoscale junctions utilizing thin-film edges. As a result, there is no diffusion of Ni and Fe atoms into PEN substrates, resulting in clear and smooth formation of the interface. The surface roughness is also as small as 0.28-0.37 nm in the same scanning scale as the film thickness. As for the magnetic properties, the squareness of the hysteresis loop is as small as 0.24 for Ni/PEN, where there is no observation of the anisotropy magnetoresistance (AMR) effect. In contrast, the squareness of the hysteresis loop is as large as 0.95 for Ni75Fe25/PEN, where the AMR effect has been successfully obtained. These experimental results indicate that Ni 75Fe25/PEN is a promising material for use in electrodes of nanoscale junctions from the viewpoint of structural and magnetic properties.
• Surface Roughness and Magnetic Properties of Ni and Ni78Fe22 Thin Films on Polyethylene Naphthalate Organic Substrates

  Hideo Kaiju, Nubla Basheer, Kenji Kondo, Akira Ishibashi

  IEEE TRANSACTIONS ON MAGNETICS 46 6 1356 - 1359 2010年06月 [査読有り][通常論文]
   

  We have studied structural, electrical, and magnetic properties of Ni and Ni78Fe22 thin films evaporated on polyethylene naphtalate (PEN) organic substrates towards the fabrication of spin quantum cross (SQC) devices. As we have investigated the scaling properties on the surface roughness, the surface roughness of Ni (16 nm)/PEN is 0.34 nm, corresponding to 2 or 3 atomic layers, in the scanning scale of 16 nm, and the surface roughness of Ni78Fe22 (14 nm)/PEN is also as small as 0.25 nm, corresponding to less than 2 atomic layers, in the scanning scale of 14 nm. These facts denote that Ni/PEN and Ni78Fe22/PEN are suitable for magnetic electrodes on organic substrates used for SQC devices from the viewpoint of the surface morphology. Then, we have investigated magnetic hysteresis curve and magnetoresistance effects for Ni/PEN and Ni78Fe22/PEN. The squareness of the hysteresis loop is as small as 0.24 for Ni (25 nm)/PEN, where there is no observation of the anisotropy magnetoresistance (AMR) effect. In contrast, the squareness of the hysteresis loop is as large as 0.86 for Ni78Fe22 (26 nm)/PEN, where the AMR effect has been successfully obtained. These experimental results indicate that Ni78Fe22/PEN is a promising material for use in SQC devices from the viewpoint of not only the surface morphologies but also magnetic properties.
• Theoretical Modeling of Spin Quantum Cross Structure Devices with Noncollinear Ferromagnetic Electrodes

  Kenji kondo

  J. Appl. Phys. 107 09C709-1 - 09C709-3 2010年04月 [査読有り][通常論文]
  
• The fabrication of Ni quantum cross devices with a 17 nm junction and their current-voltage characteristics

  Hideo Kaiju, Kenji Kondo, Akito Ono, Nobuyoshi Kawaguchi, Jonghan Won, Akihiko Hirata, Manabu Ishimaru, Yoshihiko Hirotsu, Akira Ishibashi

  NANOTECHNOLOGY 21 1 015301-1 - 015301-6 2010年01月 [査読有り][通常論文]
   

  Quantum cross (QC) devices which consist of two Ni thin films deposited on polyethylene naphthalate substrates with their edges crossing have been fabricated and their current-voltage characteristics have been investigated. The cross-sectional area between the two Ni electrodes, which was obtained without the use of electron-beam or optical lithography, can be as small as 17 nm x 17 nm. We have successfully obtained ohmic current-voltage characteristics, which show good agreement with calculation results within the framework of the modified Anderson model. The calculated results also predict a high switching ratio in excess of 100000:1 for QC devices having the molecule sandwiched between the Ni electrodes. This indicates that QC devices having the molecule can be expected to have potential application in novel switching devices.
• A Theoretical Study and Realization of New Spin Quantum Cross Structure Devices using Organic Materials

  Kenji Kondo

  Mater. Res. Soc. Symp. Proc. 1198 E07011 - E07016 2010年 [査読有り][通常論文]
  
• Fabrication and Current-Voltage Characteristics of Ni Spin Quantum Cross Devices with P3HT:PCBM Organic Materials

  Mater. Res. Soc. Symp. Proc. 1252 J02081 - J02086 2010年 [査読有り][通常論文]
  
• Current-Voltage Characteristics in Nanoscale Tunnel Junctions Utilizing Thin-Film Edges

  Hideo Kaiju, Kenji Kondo, Akira Ishibashi

  JAPANESE JOURNAL OF APPLIED PHYSICS 49 10 105203-1 - 105203-5 2010年 [査読有り][通常論文]
   

  We have derived a formula for current density-voltage (J-V) characteristics in nanoscale tunnel junctions, consisting of thin insulating barriers sandwiched between two thin metal films whose edges are crossing. As a result of the calculation of J-V characteristics, the current density decreases with decreasing the metal thickness below 30-40nm due to the quantization of the out-of-plane direction in the metal films. Moreover, as a result of the fabrication of Ni/NiO/Ni nanoscale tunnel junctions with a junction area of 24 x 24 nm(2), we have found that experimental J-V characteristics show a good fit to calculation results with a barrier height of 0.8 eV and a barrier thickness of 0.63 nm. These results indicate that the derived formula is useful for the evaluation of the barrier height and the barrier thickness and our fabrication method can be expected as a new technique for the creation of nanoscale tunnel junctions. (C) 2010 The Japan Society of Applied Physics
• Theoretical and experimental results of electronic transport of spin quantum cross structure devices

  Kenji Kondo, Hideo Kaiju, Akira Ishibashi

  JOURNAL OF APPLIED PHYSICS 105 7 07D5221 - 07D5223 2009年04月 [査読有り][通常論文]
   

  Recently, we have proposed quantum cross structure (QCS) devices that consist of two metal thin films deposited on organic films with edge-to-edge configuration like crossed fins for switching devices. In this paper, we propose a spin quantum cross structure (SQCS) device, which is a QCS device consisting of two magnetic thin films. We show theoretical and experimental results of electronic transport characteristics regarding SQCS devices. The calculation of the I-V characteristics has been performed for the SQCS devices with the Ni magnetic thin films for both the electrodes within the framework of the Anderson model. Then, we fabricated a SQCS device with the Ni magnetic thin films and measured the I-V characteristics by a four-terminal method. Also, the calculation of the magnetoresistance ratio has been done as a function of renormalized transfer matrices including magnetostriction effects and the other effects phenomenologically. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3072781]
• Ni thin films vacuum-evaporated on polyethylene naphthalate substrates with and without the application of magnetic field

  Hideo Kaiju, Akito Ono, Nobuyoshi Kawaguchi, Kenji Kondo, Akira Ishibashi, Jonghan Won, Akihiko Hirata, Manabu Ishimaru, Yoshihiko Hirotsu

  APPLIED SURFACE SCIENCE 255 6 3706 - 3712 2009年01月 [査読有り][通常論文]
   

  We study the structural properties of the surface roughness, the surface mound size and the interfacial structure in Ni thin films vacuum-deposited on polyethylene naphthalate (PEN) organic substrates with and without the application of magnetic field and discuss its feasibility of fabricating quantum cross (QC) devices. For Ni/PEN evaporated without the magnetic field, the surface roughness decreases from 1.3 nm to 0.69 nm and the surface mound size increases from 32 nm to 80 nm with the thickness increased to 41 nm. In contrast, for Ni/PEN evaporated in the magnetic field of 360 Oe, the surface roughness tends to slightly decrease from 1.3 nm to 1.1 nm and the surface mound size shows the almost constant value of 28-30 nm with the thickness increased to 35 nm. It can be also confirmed for each sample that there is no diffusion of Ni into the PEN layer, resulting in clear Ni/PEN interface and smooth Ni surface. Therefore, these experimental results indicate that Ni/PEN films can be expected as metal/insulator hybridmaterials in QC devices, leading to novel high-density memory devices. (C) 2008 Elsevier B.V. All rights reserved.
• Fabrication of Quantum Cross Devices Using Ni Thin Films on Polyethylene Naphthalate Organic Substrates

  J. Magn. Soc. Jpn. 33 3 242 - 246 2009年 [査読有り][通常論文]
  
• Study of Gold Thin Films Evaporated on Polyethylene Naphthalate Films toward the Fabrication of Quantum Cross Devices

  Hideo Kaiju, Akito Ono, Nobuyoshi Kawaguchi, Kenji Kondo, Akira Ishibashi

  NANOSCALE PHENOMENA IN FUNCTIONAL MATERIALS BY SCANNING PROBE MICROSCOPY 1025 B07011 - B07016 2008年 [査読有り][通常論文]
   

  We have studied Au thin films evaporated on polyethylene naphtalate (PEN) organic substrates as a function of Au thickness < similar to 20 nm and discussed its feasibility toward metal/insulator hybrid materials used for quantum cross devices using atomic force microscope. The Au grain size increases from 28.0 +/- 4.6 nm to 48.5 +/- 11.4 nm with increasing the Au thickness from 6.9 to 20.8 nm and it denotes that the Au grain size is larger than its Au-thickness size, respectively. The surface roughness of Au films of sub-15-nm thickness, in the scanning scale of the Au-thickness size, is less than 0.9 nm, corresponding to 4-5 atomic layers. These experimental results indicate that Au thin films on PEN substrates are suitable for possible metal/insulator hybrid materials to be used in quantum cross devices.
• Theoretical Investigation of New Quantum-Cross-Structure Device as a Candidate beyond CMOS

  Kenji Kondo, Hideo Kaiju, Akira Ishibashi

  Mater. Res. Soc. Symp. Proc. 1067 B03011 - B03016 2008年 [査読有り][通常論文]
  
• High cleanliness of portable clean-unit-box to unite clean-unit system platforms (CUSPs) and CUSP units

  Md. D. Rahaman, K. Gomita, N. Kawaguchi, H. Kaiju, K. Kondo, A. Ishibashi

  ELECTRONICS LETTERS 43 24 1356 - 1357 2007年11月 [査読有り][通常論文]
   

  As a platform for nano-science and technology, cleanliness in a compact and local clean environment, i.e. a portable clean-unit-box (CUP), is reported for establishing a large-scale network of an ultra-high clean environment platform towards cross-disciplinary research. Analyses of experimental results indicate that the CUP has cleanliness of ISO class similar to 2, which is one order of magnitude better than the conventional wafer transportation cleanbox.
• Analysis of origin of offset seen in astigma method when we read land-groove disk

  Kenji Kondo

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 46 1 229 - 231 2007年01月 [査読有り][通常論文]
   

  When we read a land-groove disk using the astigma method, we notice that the error signal has an offset. This offset makes the astigma method unavailable. We have simulated the focus-error signal using the diffraction theory and found the origin of the offset. The origin of the offset is attributed to the distorted reflected images from both land and groove. Similarly to the case of a dielectric multilayer, we can consider that the land-groove disk has an effective mirror surface which corresponds to the concept of an effective refractive index. The distorted reflected images from both land and groove are caused by the defocus from the effective mirror surface.
• Energy spectrum of two-dimensional electron gas to be used in quantum cross structures

  Kenji Kondo, Akira Ishibashi

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 45 12 9137 - 9139 2006年12月 [査読有り][通常論文]
   

  A quantum cross system consisting of the edge-to-edge configuration of two-dimensional (2D) conductors is expected to serve as an ideal platform for molecular electronic devices. As the first step, we have calculated the electron energy spectrum of 2D electron gas at a GaAs/AlGaAs heterointerface as a candidate for the 2D conductor in the quantum cross, taking into consideration the electron correlation for the 2D electron system. As a result, we have confirmed that a plasmaron can exist stably. This means that we will observe the broadening of the conductance peak due to the scattering induced by plasmons when we measure the current-voltage characteristics of the quantum cross device.
• Quantum-Cross Tunneling Junction for High Density Memory

  Hideo Kaiju, Kenji Kondo, Akira Ishibashi

  MRS Proceedings 961 2006年 [査読有り][通常論文]
   

  We calculated transport properties of edge-to-edge quantum cross structure that consists of two metal nano-ribbons having edge-to-edge configuration with a tunnel barrier and showed current-voltage characteristics depending on the metal-ribbon thickness (5-30 nm), the barrier height (0.5-1.5 eV) and the barrier thickness (0.5-1.0 nm). Interesting behavior of transport properties is that the metal-ribbon thickness affects the current density due to the quantization of nano-ribbon and also the current density, being dependent on the barrier height and the barrier thickness, decreases with high and thick barrier. These calculated results indicate that we can precisely obtain the information on the material sandwiched between two electrodes, such as the barrier height and the barrier thickness, by a fit of experimental data to our derived equation, and these approaches result in a distinction between the sandwiched material and the electrode.
• Current-injection induced dislocation networks in II-VI laser diodes: bottom-up structures emerging in top-down system

  A Ishibashi, K Kondo

  ELECTRONICS LETTERS 40 20 1268 - 1269 2004年09月 [査読有り][通常論文]
   

  By controlling the location of staking faults and adjusting the amount of electron-hole injection in pn-junction, structural connection between a bottom-up structure of dislocations and a top-down structure of diodes can be made in a controlled manner. The possibility of uniting bottom-up structures with top-down system is demonstrate.
• Deep UV mastering with a write compensation technique realizing over 20 GB/layer capacity disc

  M Takeda, M Furuki, T Ishimoto, K Kondo, M Yamamoto, S Kubota

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 39 2B 797 - 799 2000年02月 [査読有り][通常論文]
   

  Recent progress in blue laser diodes has necessitated the development of ultra-high density mastering corresponding to a density several times higher than that of the digital versatile disk (DVD). As reported earlier, we developed a deep UV master recorder using an all-solid-state 266 nm laser, and confirmed an acceptable RF signal read-out quality from 20 Gbytes capacity with CD disc size, of which the bit density is equal to 14 Gbit/inch(2). Here, we report the improvement of RF signal jitter utilizing a write compensation technique for the mastering process. In this technique, the positions of the leading and trailing edges of the signal are shifted by pit signal processing (PSP). We confirmed an improved quality read-out signal of which the bottom jitter value is less than 8% from the 20 Gbytes disc, and also analyzed the signal jitter elements. In addition, experimental results of significantly higher densities of up to 30 Gbytes (21 Gbit/inch(2)) are demonstrated.
• Deep UV mastering using an all-solid-state 266 nm laser for an over 20 GBytes/layer capacity disk

  M Takeda, M Furuki, H Yamatsu, T Kashiwagi, Y Aki, A Suzuki, K Kondo, M Oka, S Kubota

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 38 3B 1837 - 1838 1999年03月 [査読有り][通常論文]
   

  The deep UV mastering process of the next generation high density disk is demonstrated for the first time using an all-solid-state continuous-wave 266 nm laser. We have developed a novel deep UV master recorder with a laser source. and achieved a density of 20 Gbytes capacity (14 Gbit/inch(2)) with acceptable jitter for the compact disk size.
• Deep UV mastering with a write compensation technique realizing over 20GB/layer capacity disc

  M Takeda, M Furuki, T Ishimoto, K Kondo, M Yamamoto, S Kubota

  JOINT INTERNATIONAL SYMPOSIUM ON OPTICAL MEMORY AND OPTICAL DATA STORAGE 1999 3864 2 - 4 1999年 [査読有り][通常論文]
  
• Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state-laser using β-BaB2O4

  K. Kondo, M. Oka, H. Wada, T. Fukui, N. Umezu, K. Tatsuki, S. Kubota

  Opt. Lett. 23 195 - 197 1998年04月 [査読有り][通常論文]
  
• An all-solid-state continuous-wave 266nm laser for optical disk mastering

  M Oka, M Takeda, T Kashiwagi, M Yamamoto, M Sakamoto, K Kondo, K Tatsuki, S Kubota

  OPTICAL DATA STORAGE '98 3401 TuA2・47-49 44 - 47 1998年 [査読無し][通常論文]
   

  All-solid-state cw 266 nm laser operates >1000 hours with diffraction-limited beam and low noise output (-130dB/Hz), which is suitable for next-generation disk mastering.
• Reliability of Czochralski-grown beta-BaB2O4 (BBO) devices

  M Umezu, T Fukui, T Okamoto, H Wada, K Tatsuki, K Kondo, S Kubota

  LASER-INDUCED DAMAGE IN OPTICAL MATERIALS: 1997, PROCEEDINGS 3244 124 - 129 1998年 [査読有り][通常論文]
   

  We report the first operation of more than 1000 hours of continuous wave (CW) 100-mW output at 266 nm which was frequency-quadrupled from a Nd:YAG or a Nd:YVO4 laser. We used a Czochralski (Cz)-grown beta-BaB2O4 (BBO) crystal device to double a 532-nm wave in an external ring cavity. The round trip cavity loss increasing rate was 7.6 x 10(-5) %/hour at a 266-nm power density of 270 W/cm(2). The UV range optical transmission loss of the Cz-grown crystal was evaluated. The optical loss of the Cz-grown crystal for e-ray at 266 nm was improved td 2 %/cm, which was half of the crystal grown by the top seeded solution growth (TSSG) method. The degradation rate, delta(p) = (dP(4w)(t)/dt)/P-4w(0), was also evaluated in 30 MW/cm(2) of 266-nm generation from a Q-switched Nd:YAG laser. The delta(p) of Ct-crystal was typically 0.1 %/hour, which was one order of magnitude lower than that of the TSSG-crystals. The fabrication process was also improved. Our system with the crystal device can be put to practical use in the areas of photolithography, material processing and ultra high-density optical disk mastering.
• Relation between hole density and impurity density in ZnMgSSe semiconductors

  K. Kondo, H. Okuyama, A. Ishibashi

  Applied Physics Letters 64 25 3434 - 3436 1994年06月20日 [査読有り][通常論文]
  
• A study of internal absorption in Zn(Cd)Se/ZnMgSSe semiconductor lasers

  K. Kondo, M. Ukita, H. Yoshida, Y. Kishita, H. Okuyama, S. Ito, T. Ohata, K. Nakano, A. Ishibashi

  Journal of Applied Physics 76 5 2621 - 2626 1994年 [査読有り][通常論文]
   

  Based on two different experiments and an optical field calculation, we show that the free-carrier absorption αfc in Zn(Cd)Se/ZnMgSSe semiconductor lasers is about 4 cm-1 and that it is smaller than that of GaAs/AlGaAs semiconductor lasers. We have measured the dependence of the L-I characteristics on the cavity length of double heterostructure (DH) lasers under photopumped operation and of single quantum well-separate confinement heterostructure (SQW-SCH) lasers under current-injected operation. For the DH laser, the total absorption coefficient αi and β×J0 product (β is a gain constant, and J0 is the nominal current density that makes the gain equal to zero) are estimated to be 4.2 cm-1 and 8.6×10 cm-1, respectively. For the SQW-SCH laser, αi, β, and J0 are estimated to be 21 cm-1, 4.23×10-3 cm×μm/A, and 1.9×10-3 A/(cm2×μm), respectively. By calculating the optical fields of these lasers, we have estimated that the absorption in a GaAs substrate is 16.53 cm-1 in the SQW-SCH laser and that it is negligible in the DH laser. We have shown that the large loss in the SQW-SCH laser is caused by both αfc and the absorption in the substrate and that αi in the DH laser is caused only by free carrier absorption.

書籍

• RECENT RESEARCH DEVELOPMENTS IN APPLIED PHYSICS, “Recent advances in magnetic thin films on flexible organic substrates”

  H. Kaiju, K. Kondo, M. Ishimaru, Y. Hirotsu, A. Ishibashi (担当:共著)
  Transworld Research Network 2012年 2012年
• ホール効果と異常ホール効果, そしてその先にあるもの

  近藤 憲治 (担当:単著範囲:The Japan Institute of Metals and Materials)
  日本金属学会 2009年02月
• ナノデバイスの現状と低次元電子ガスの理論的特性

  近藤 憲治 (範囲:Chemical Industry Co.)
  化学工業社 2008年06月

講演・口頭発表等

• A Weak Phase of Second-Order Topological Insulators  [通常講演]

  S. Komori, K. Kondo

  The 4th International Symposium for The Core Research Cluster for Spintronics 2021年02月 ポスター発表
• 2次のWeyl半金属の電子状態と磁気輸送特性に関する研究  [通常講演]

  小森 至瑠, 近藤 憲治

  第25回半導体におけるスピン工学の基礎と応用 (PASPS-25) 2020年11月
• A Study of Magnetoresistance in Type-I and Type-II Weyl Semimetals  [通常講演]

  森島一輝, 近藤憲治

  The 65th Annual Conference on Magnetism and Magnetic Materials (MMM 2020) 2020年11月 ポスター発表
• Magnetotransport Characteristics in Second-order Weyl Semimetals  [通常講演]

  小森至瑠, 近藤憲治

  The 65th Annual Conference on Magnetism and Magnetic Materials (MMM 2020) 2020年11月 ポスター発表
• 2次のワイル半金属のエキゾティックな電子状態に関する研究  [通常講演]

  小森 至瑠, 近藤 憲治

  第6回北海道大学部局横断シンポジウム 2020年10月 ポスター発表
• Type-I 及びType-II ワイル半金属における磁気抵抗効果の違いに関する研究  [通常講演]

  森島 一輝, 近藤 憲治

  第6回北海道大学部局横断シンポジウム 2020年10月 ポスター発表
• 2 次のType-II Weyl 半金属で現れるFermi Arc  [通常講演]

  小森 至瑠, 近藤 憲治

  2020年日本物理学会秋大会 2020年09月 口頭発表（一般）
• Type-I 及びType-II ワイル半金属における磁気抵抗効果の違いに関する研究  [通常講演]

  森島一輝, 近藤 憲治

  2020年日本物理学会秋大会 2020年09月 口頭発表（一般）
• Higher-Order Topological Insulator Taking into Consideration Uniaxially Anisotropic Hopping  [通常講演]

  S. Komori, K. Kondo

  The 64th Annual Conference on Magnetism and Magnetic Materials(MMM2019) 2019年11月
• Topological Hall Effects and Topological Spin Hall Effects Caused by a Skyrmion and a Skyrmionium  [通常講演]

  Y. Ishida, K. Kondo

  The 64th Annual Conference on Magnetism and Magnetic Materials(MMM2019) 2019年11月
• 一軸異方性を有するホッピングが高次トポロジカル絶縁体へ与える影響  [通常講演]

  小森 至瑠, 近藤 憲治

  第80回 応用物理学会秋季学術講演会 2019年09月 口頭発表（一般）
• スカーミオンによるトポロジカル・ホール効果及びトポロジカル・スピン・ホール効果  [通常講演]

  石田 雄一, 近藤 憲治

  第80回 応用物理学会秋季学術講演会 2019年09月 口頭発表（一般）
• Type-Ⅱワイル半金属におけるフェルミアーク  [通常講演]

  森島 一輝, 近藤 憲治

  第80回 応用物理学会秋季学術講演会 2019年09月 口頭発表（一般）
• 高次トポロジカル絶縁体で発現するヒンジ状態のロバスト性  [通常講演]

  小森 至瑠, 近藤 憲治

  日本物理学会第74回年次大会（2019年） 2019年03月
• 2種類の原子を加えたHoneycombナノリボンにおける2次元量子スピンホール相の研究  [通常講演]

  伊藤 蓮, 近藤 憲治

  第66回応用物理学会春季学術講演会 2019年03月
• Manifestation of Quantum Anomalous Hall Phase in Modified Qi-Wu-Zhang Model  [通常講演]

  S. Komori, K. Kondo

  The 19th RIES-HOKUDAI International Symposium "So" 2018年12月
• A Study of Fermi Arcs for Weyl Semimetals and Line-Node Semimetals  [通常講演]

  R. Itoh, K. Kondo

  The 19th RIES-HOKUDAI International Symposium "So" 2018年12月
• Influence of the Gilbert Damping Constant on the Skyrmion Hall Effect  [通常講演]

  Y. Ishida, K. Kondo

  The 19th RIES-HOKUDAI International Symposium "So" 2018年12月
• A Dependence of the Skyrmion Hall Effect on the Gilbert Damping Constant"  [通常講演]

  Y. Ishida, K. Kondo

  2018 International Conference on Solid State Devices and Materials (SSDM2018) 2018年09月
• Normal Forms in Singularity Theory for Geometric Classifications of Band Structures  [通常講演]

  Hiroshi Teramoto, Asahi Tsuchida, Yutaro Kabata, Kenji Kondo, KatsusukeNabeshima, ShyūichiIzumiya, Mikito Toda, Tamiki Komatsuzaki

  Dynamics Days Europe 2018 2018年09月
• Fermi arcs for Weyl semimetals and line-node semimetals in topological insulator superlattice  [通常講演]

  R. Itoh, K. Kondo

  10th International School and Conference on Physics and Applications of Spin Phenomena in Solids (PASPS10) 2018年08月
• フォトン・フォトキャリア直交型マルチストライプ 半導体太陽電池に向けた 周期配列放物線鏡付テイパー非対称導波路構造  [通常講演]

  石橋 晃, 河西 剛, 近藤 憲治, 澤村 信雄

  日本応用物理学会 2018年春季大会 2018年03月
• トポロジカル絶縁体超格子におけるフェルミアーク  [通常講演]

  伊藤 蓮, 近藤 憲治

  第65回応用物理学会春季学術講演会(東京都西新宿) 2018年03月
• An Arbitrary Order Effective Hamiltonian of Hexagonal Warping Effects of Dirac Cone  [通常講演]

  K. Kondo, H. Teramoto

  The 62nd Annual Conference on Magnetism and Magnetic Materials 2017年11月
• ディラック・コーンのヘキサゴナルな歪みの効果に対する任意次数の有効ハミルトニアンの導出  [通常講演]

  伊藤蓮, 寺本央, 近藤憲治

  応用物理学会秋季学術講演会講演予稿集(CD-ROM) 2017年08月
• Topological Spin Currents in Graphene Nanoribbons  [通常講演]

  R. Itoh, K. Kondo

  Spintech IX 2017年06月
• Symmetric and Asymmetric Wave-guides for Multi-striped Orthogonal Photon-Photocarrier-Propagation Solar Cells (MOP3SC)  [通常講演]

  A. Ishibashi, H. Kobayashi, N. Sawamura, K. Kondo, T. Kasai

  2017 IEEE International Conference on Applied System Innovation (IEEE ICASI 2017) 2017年05月
• 非対称導波路結合フォトン・フォトキャリア直交型マルチストライプ半導体太陽電池用周期配列放物線鏡の作製  [通常講演]

  石橋 晃, 澤村 信雄, 近藤 憲治, 河西 剛

  日本応用物理学会 2017年春季大会 2017年03月
• グラフェンナノリボンと量子スピンホール相  [通常講演]

  伊藤 蓮, 近藤 憲治

  2017年 第64回応用物理学会春季学術講演会 2017年03月
• A Revisit of Quantum Spin Hall Effect in Graphene  [通常講演]

  R. Itoh, K. Kondo

  The 17th RIES-HOKUDAI INTERNATIONAL SYMPOSIUM on 柔 2016年12月
• A Warping Effect of Dirac Cone by the Perturbation up to 5th Order under the Symmetry of C3v  [通常講演]

  K. Kondo, H. Teramoto

  The 61st Annual Conference on Magnetism and Magnetic Materials 2016年11月
• C_3v_対称性の下での5次摂動によるDirac Coneのワーピング  [通常講演]

  近藤 憲治, 寺本 央

  2016年日本物理学会秋季大会 2016年09月
• 非対称導波路結合フォトン・フォトキャリア直交型マルチストライプ半導体太陽電池  [通常講演]

  石橋 晃, 河西 剛, 近藤 憲治, 澤村 信雄

  日本応用物理学会 2016年春季大会 2016年03月
• C_3v対称性の下での5次摂動によるDirac Coneのワーピング  [通常講演]

  近藤 憲治, 寺本 央

  日本物理学会講演概要集 2016年 一般社団法人 日本物理学会
   

  <p>Bi_2_Te_3_における表面の電子状態のヘキサゴナルなワーピングを解明するFuの論文により、実験によるDirac-Coneの歪みの理解が進んだ。しかしながら、特異点論の考察から、3次摂動ではミニマルなモデルではないことがわかり、3次より高次の摂動を考慮した場合、質的な変化も起こりうるので、5次までの摂動計算を行った。その結果、質的な変化はないが、有意な定量的な変化がエネルギーバンドならびにスピン分布にもたらされたので、報告する。</p>
• 3次のRashbaスピン軌道相互作用下での量子ドットからなるアハラノフ・ボーム・リングにおけるスピンフィルタリング効果  [通常講演]

  近藤 憲治

  日本物理学会秋季大会2015 2015年09月
• 任意の次数のRashbaスピン軌道相互作用下における2個の量子ドットが埋め込まれたAharonov-Bohmリングにおけるスピンフィルタリング  [通常講演]

  近藤 憲治

  第76回応用物理学会秋季学術講演会 2015年09月
• Spin filtering in Double Quantum Dots Aharonov-Bohm Ring under Cubic Rashba Spin Orbit Interaction  [通常講演]

  Kenji Kondo

  The 20th International Conference on Magnetism 2015年07月
• AC impedance characteristics of Co/Alq3/Ni75Fe25 junctions  [通常講演]

  T. Sakashita, Y. Kamaya, H. Kaiju, K. Kondo, A. Ishibashi

  The 15th Ries-Hokudai International Symposium joined with the 3rd International Symposium of Nano-Macro Materials, Devices, and System Research Alliance Project 2014年12月
• Validity of the Free Electron Model for Two-Dimensional Electrodes  [通常講演]

  Kenji Kondo

  2014 MRS Fall Meeting 2014年12月
• フォトンフォトキャリア直交型高効率太陽電池用導波路の検討  [通常講演]

  谷口 朝哉, 河西 剛, 近藤 憲治, 石橋 晃

  第75回応用物理学会秋季学術講演会 2014年09月
• Ni75Fe25/Alq3/Co接合における交流インピーダンス特性  [通常講演]

  坂下 友規, 釜谷 悠介, 海住 英生, 近藤 憲治, 石橋 晃

  第75回応用物理学会秋季学術講演会 2014年09月
• 障壁を介したトポロジカル絶縁体から半導体へのスピン注入  [通常講演]

  近藤 憲治

  2014年日本物理学会秋季大会 2014年09月
• Negative Magnetoresistance in Ferromagnet/Semiconductor/Ferromagnet Structures with Cubic Dresselhaus Spin-Orbit-Interaction  [通常講演]

  Kenji Kondo

  The 14th RIES-Hokudai International Symposium 2013年12月
• Fabrication of Ni-based Nanoscale Junctions Utilizing Thin-Film Edges and Their Structural and Electrical Properties  [通常講演]

  H. Kaiju, K. Kondo, M. Ishimaru, Y. Hirotsu, A. Ishibashi

  The 2013 Energy, Materials and Nanotechnology Fall Meeting 2013年12月
• Spin transport in normal metal/insulator/topological insulator coupled to ferromagnetic insulator structures  [通常講演]

  Kenji Kondo

  The 58th Annual Magnetism and Magnetic Materials Conference 2013年11月
• 2次元金属電極における自由電子近似の妥当性  [通常講演]

  近藤 憲治

  日本物理学会秋季大会2013 2013年09月
• 集光型磁気光学Kerr効果によるCo/PENの磁気光学定数の決定と表面磁性  [通常講演]

  近藤 憲治, 海住 英生, 石橋 晃

  日本物理学会秋季大会2013 2013年09月
• Co/PENにおける面内磁気光学カー効果の回転磁場依存性  [通常講演]

  海住 英生, 近藤 憲治, 阿部 太郎, 石橋 晃

  日本物理学会秋季大会 2013年09月
• Co/Alq3/Ni75Fe25接合における電気・磁気・構造特性  [通常講演]

  釜谷 悠介, 海住 英生, 近藤 憲治, 石橋 晃

  日本物理学会秋季大会 2013年09月

その他活動・業績

• Classification of Hamiltonians in neighborhoods of band crossings in terms of the theory of singularities (vol 58, 073502, 2017)

  Hiroshi Teramoto, Kenji Kondo, Shyuichi Izumiya, Mikito Toda, Tamiki Komatsuzaki JOURNAL OF MATHEMATICAL PHYSICS 60 (12) 2019年12月

特許

• 特許第3277711号:半導体レーザ及びその製造方法  2002年02月15日

  丸谷 幸利, 小林 俊雅, 近藤 憲治, 根本 和彦, 樋口 慶信  ソニー株式会社  200903022624077503
• 特開平11-109426:安定共振器を有する光学系  1999年04月23日

  和田 裕之, 増田 久, 近藤 憲治, 岡 美智雄  ソニー株式会社  200903040487288630
• 特開平11-087814:レーザ共振器の寿命延長方法  1999年03月30日

  近藤 憲治, 岡 美智雄  ソニー株式会社  200903010729572870
• 特開平11-064904:レーザ光発生装置  1999年03月05日

  近藤 憲治, 岡 美智雄  ソニー株式会社  200903081768900995
• 特開平7-254756:光デバイス  1995年10月03日

  近藤 憲治  ソニー株式会社  200903092546206154
• 特開平7-056031:多層膜中の導波光シミュレーション方法  1995年03月03日

  近藤 憲治  ソニー株式会社  200903096770257738
• 特開平5-226784:半導体レーザーの駆動方法  1993年09月03日

  岩本 浩治, 近藤 憲治  ソニー株式会社  200903023650796611
• 特許US-6404786:Laser beam generating apparatus  

  近藤 憲治
• 特許US-5572539:II-VI semiconductor laser with different guide layers  

  近藤 憲治

受賞

• 1998年 ISOM 優秀論文賞
  

共同研究・競争的資金等の研究課題

• スピン軌道トルクによるハーフメタル強磁性体磁化制御とそのデバイス応用

  文部科学省：科学研究費補助金(基盤研究(B))

  研究期間 : 2017年04月 -2020年03月 

  代表者 : 植村 哲也

   

  分担者：近藤憲治
• 量子ドット内蔵光ファイバーを用いた光子を介する遠隔電子スピン間制御

  文部科学省：科学研究費補助金(基盤研究(B))

  研究期間 : 2016年04月 -2020年03月 

  代表者 : 笹倉 弘理

   

  分担者：近藤憲治、熊野英和
• トポロジカルな性質を持つ物質とその応用の研究

  東北大学スピントロニクス学術連携研究教育センター(CSRN)：CSRN提案共同プロジェクト

  研究期間 : 2016年04月 -2019年03月 

  代表者 : 近藤 憲治
• スピン軌道相互作用が強い物質及び現象のトポロジーに基づく研究とスピン素子への応用

  文部科学省：科学研究費補助金(基盤研究(C))

  研究期間 : 2016年 -2019年 

  代表者 : 近藤 憲治
• 位相不変量をもつスピン現象の理論研究及びその応用デバイスの設計

  文部科学省：科学研究費補助金(基盤研究(C))

  研究期間 : 2012年04月 -2015年03月 

  代表者 : 近藤 憲治
• フォトン・フォトキャリア直交型マルチストライプ半導体光電変換素子の研究

  文部科学省：科学研究費補助金(基盤研究(B))

  研究期間 : 2010年 -2012年 

  代表者 : 石橋 晃, 近藤 憲治, 海住 英生
• スピン伝導の基礎理論構築と新規なデバイスの設計

  文部科学省：科学研究費補助金(基盤研究(C))

  研究期間 : 2009年 -2011年 

  代表者 : 近藤 憲治, 海住 英生
• 量子井戸や量子細線などのナノ空間での電子相関の理論的解明

  北海道大学電子科学研究所：若手育成研究費

  研究期間 : 2003年04月 -2005年03月 

  代表者 : 近藤 憲治

教育活動情報

主要な担当授業

大学運営

委員歴

• 2014年06月 - 現在   Scientific Reports (Nature Publishing Group)   Editorial Board Member
• 2020年04月 - 2022年03月   スピントロニクス専門研究会   世話人
• 2016年12月 - 2016年12月   PASPS21 世話人
• 2007年04月 - 2007年09月   日本物理学会   第62回年次大会 実行委員

その他

• 2021年10月 - 2021年10月  北海道大学プレスリリース 「カイラルアノマリー 公式の拡張に成功」