1998, ISOM, Excellent Paper Award　　　　　　　　　　　　　　　

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, AIP Publishing, 29 Sep. 2021, [Peer-reviewed], [Last author, Corresponding author]
Scientific journal

A comparison of magnetoconductivities between type-I and type-II Weyl semimetals
K. Morishima, K. Kondo
Journal of Applied Physics, 129, 12, 125104, 125104, AIP Publishing, 28 Mar. 2021, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal, 11648791

A proposal of strong and weak phases in second-order topological insulators
Shiryu Komori, Kenji Kondo
Journal of Physics Communications, 4, 12, 125005-1, 125005-12, IOP Publishing, 14 Dec. 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, Accepted Manuscript, 12776226

Theoretical comparison between skyrmion and skyrmionium motions for spintronics applications
Ishida, Yuichi, KONDO, Kenji
Japanese Journal of Applied Physics, 59, SGGI04-1, SGGI04-7, 20 Feb. 2020, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

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, Journal of Singularities, Jan. 2020, [Peer-reviewed]
English, Scientific journal

An Effect of the Gilbert Damping Constant on the Skyrmion Hall effect
Ishida Yuichi, KONDO Kenji
Journal of Magnetism and Magnetic Materials,, 493, 1, 165687-1, 165687-7, Jan. 2020, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Quantum spin Hall phase in honeycomb nanoribbons with two different atoms: edge shape effect to bulk-edge correspondence
Kenji Kondo, Ren Ito
J. Phys. Commun., 3, 055007-1, 055007-12, May 2019, [Peer-reviewed], [Lead author, Corresponding author]
English

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, Feb. 2019, [Peer-reviewed]
English, Scientific journal

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, Institute of Electrical and Electronics Engineers Inc., 21 Jul. 2017, [Peer-reviewed]
English, International conference proceedings, 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, AMER INST PHYSICS, Jul. 2017, [Peer-reviewed]
English, Scientific journal, 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, 3D Display Research Center, 01 Dec. 2016, [Peer-reviewed]
English, Scientific journal, 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　　　　　　　　　　　　　　　
KONDO Kenji
SPIN, World Scientifc Publishing, Oct. 2016, [Peer-reviewed], [Invited], [Lead author, Corresponding author]
English, Scientific journal

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, IOP PUBLISHING LTD, Apr. 2016, [Peer-reviewed]
English, Scientific journal, 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, [Peer-reviewed]

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, IOP PUBLISHING LTD, Dec. 2015, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, 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, Materials Research Society, 2015, [Peer-reviewed], [Lead author, Corresponding author]
English, International conference proceedings, 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, Jul. 2014, [Peer-reviewed]
English, Scientific journal

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, AMER INST PHYSICS, May 2014, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, 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, AMER INST PHYSICS, May 2014, [Peer-reviewed]
English, Scientific journal, 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, AMER INST PHYSICS, May 2013, [Peer-reviewed]
English, Scientific journal, 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, JAPAN SOC APPLIED PHYSICS, Jan. 2013, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, 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, AMER INST PHYSICS, Sep. 2012, [Peer-reviewed]
English, Scientific journal, 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, Sep. 2012, [Peer-reviewed]
English, International conference proceedings

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, AMER INST PHYSICS, Apr. 2012, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, 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, 29 Feb. 2012, [Peer-reviewed]
English, Scientific journal, 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, AMER PHYSICAL SOC, Feb. 2012, [Peer-reviewed]
English, Scientific journal, 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, [Peer-reviewed]
Japanese, International conference proceedings, 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, [Peer-reviewed], [Lead author, Corresponding author]
English, International conference proceedings, 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, [Peer-reviewed]
Japanese, International conference proceedings, 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, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, Jun. 2010, [Peer-reviewed]
English, Scientific journal, 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, Apr. 2010, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

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, IOP PUBLISHING LTD, Jan. 2010, [Peer-reviewed]
English, Scientific journal, 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, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

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, [Peer-reviewed]
English, Scientific journal

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, JAPAN SOC APPLIED PHYSICS, 2010, [Peer-reviewed]
English, Scientific journal, 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, AMER INST PHYSICS, Apr. 2009, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, 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, ELSEVIER SCIENCE BV, Jan. 2009, [Peer-reviewed]
English, Scientific journal, 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, [Peer-reviewed]
English, Scientific journal

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, MATERIALS RESEARCH SOC, 2008, [Peer-reviewed]
English, International conference proceedings, 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, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

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, INST ENGINEERING TECHNOLOGY-IET, Nov. 2007, [Peer-reviewed]
English, Scientific journal, 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, INST PURE APPLIED PHYSICS, Jan. 2007, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, 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, JAPAN SOC APPLIED PHYSICS, Dec. 2006, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, 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, Springer Science and Business Media LLC, 2006, [Peer-reviewed]
English, Scientific journal, 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, IEE-INST ELEC ENG, Sep. 2004, [Peer-reviewed]
English, Scientific journal, 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, JAPAN J APPLIED PHYSICS, Feb. 2000, [Peer-reviewed]
English, Scientific journal, 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, JAPAN J APPLIED PHYSICS, Mar. 1999, [Peer-reviewed]
English, Scientific journal, 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, SPIE-INT SOC OPTICAL ENGINEERING, 1999, [Peer-reviewed]
English, International conference proceedings

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, Apr. 1998, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

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, SPIE-INT SOC OPTICAL ENGINEERING, 1998
English, International conference proceedings, 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, SPIE-INT SOC OPTICAL ENGINEERING, 1998, [Peer-reviewed]
English, International conference proceedings, 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, AIP Publishing, 20 Jun. 1994, [Peer-reviewed], [Lead author]
English, Scientific journal

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, [Peer-reviewed]
English, Scientific journal, 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.

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, Dec. 2019
AMER INST PHYSICS, English, Others

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
Transworld Research Network 2012年, 2012, [Joint work]

Introduction to Hall Effects and Anomalous Hall Effects for the Perspective of Their Effects　　　　　　　　　　　　　　　
KONDO Kenji, The Japan Institute of Metals and Materials
日本金属学会, Feb. 2009, [Single work]

The Present Status of Nano-Devices and the Theoretical Investigation on Low Dimensional Electron Gas　　　　　　　　　　　　　　　
KONDO Kenji, Chemical Industry Co.
化学工業社, Jun. 2008

A Weak Phase of Second-Order Topological Insulators　　　　　　　　　　　　　　　
S. Komori, K. Kondo
The 4th International Symposium for The Core Research Cluster for Spintronics,, 24 Feb. 2021, English, Poster presentation
24 Feb. 2021 - 25 Feb. 2021

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　　　　　　　　　　　　　　　
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), 17 Nov. 2020
17 Nov. 2020 - 19 Nov. 2020

A Study of Magnetoresistance in Type-I and Type-II Weyl Semimetals
Kazuki Morishima, Kenji Kondo
The 65th Annual Conference on Magnetism and Magnetic Materials (MMM 2020), 04 Nov. 2020, English, Poster presentation
02 Nov. 2020 - 06 Nov. 2020, 11648791

Magnetotransport Characteristics in Second-order Weyl Semimetals
Shiryu Komori, Kenji Kondo
The 65th Annual Conference on Magnetism and Magnetic Materials (MMM 2020), 04 Nov. 2020, English, Poster presentation
02 Nov. 2020 - 06 Nov. 2020, United States, 11648791, [International presentation]

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　　　　　　　　　　　　　　　
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, 19 Oct. 2020, Japanese, Poster presentation
19 Oct. 2020 - 19 Oct. 2020

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　　　　　　　　　　　　　　　
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, 19 Oct. 2020, Japanese, Poster presentation
19 Oct. 2020 - 19 Oct. 2020

2 次のType-II Weyl 半金属で現れるFermi Arc
小森 至瑠, 近藤 憲治
2020年日本物理学会秋大会, 08 Sep. 2020, Japanese, Oral presentation
08 Sep. 2020 - 11 Sep. 2020, 11648791

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
森島一輝, 近藤 憲治
2020年日本物理学会秋大会, 08 Sep. 2020, Japanese, Oral presentation
08 Sep. 2020 - 11 Sep. 2020, 11648791

Higher-Order Topological Insulator Taking into Consideration Uniaxially Anisotropic Hopping　　　　　　　　　　　　　　　
S. Komori, K. Kondo
The 64th Annual Conference on Magnetism and Magnetic Materials(MMM2019), 06 Nov. 2019, English
[International presentation]

Topological Hall Effects and Topological Spin Hall Effects Caused by a Skyrmion and a Skyrmionium　　　　　　　　　　　　　　　
Y. Ishida, K. Kondo
The 64th Annual Conference on Magnetism and Magnetic Materials(MMM2019), 06 Nov. 2019, English
[International presentation]

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　　　　　　　　　　　　　　　
小森 至瑠, 近藤 憲治
第80回 応用物理学会秋季学術講演会, 20 Sep. 2019, Japanese, Oral presentation
[Domestic Conference]

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　　　　　　　　　　　　　　　
石田 雄一, 近藤 憲治
第80回 応用物理学会秋季学術講演会, 20 Sep. 2019, Japanese, Oral presentation
[Domestic Conference]

Type-Ⅱワイル半金属におけるフェルミアーク　　　　　　　　　　　　　　　
森島 一輝, 近藤 憲治
第80回 応用物理学会秋季学術講演会, 19 Sep. 2019, Japanese, Oral presentation
[Domestic Conference]

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　　　　　　　　　　　　　　　
小森 至瑠, 近藤 憲治
日本物理学会第74回年次大会（2019年）, 15 Mar. 2019

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　　　　　　　　　　　　　　　
伊藤 蓮, 近藤 憲治
第66回応用物理学会春季学術講演会, 12 Mar. 2019, Japanese
[Domestic Conference]

Manifestation of Quantum Anomalous Hall Phase in Modified Qi-Wu-Zhang Model　　　　　　　　　　　　　　　
S. Komori, K. Kondo
The 19th RIES-HOKUDAI International Symposium "So", 11 Dec. 2018, English
[International presentation]

A Study of Fermi Arcs for Weyl Semimetals and Line-Node Semimetals　　　　　　　　　　　　　　　
R. Itoh, K. Kondo
The 19th RIES-HOKUDAI International Symposium "So", 11 Dec. 2018, English
[International presentation]

Influence of the Gilbert Damping Constant on the Skyrmion Hall Effect　　　　　　　　　　　　　　　
Y. Ishida, K. Kondo
The 19th RIES-HOKUDAI International Symposium "So", 11 Dec. 2018, English
[International presentation]

A Dependence of the Skyrmion Hall Effect on the Gilbert Damping Constant"　　　　　　　　　　　　　　　
Y. Ishida, K. Kondo
2018 International Conference on Solid State Devices and Materials (SSDM2018), 13 Sep. 2018, English
[International presentation]

Normal Forms in Singularity Theory for Geometric Classifications of Band Structures　　　　　　　　　　　　　　　
Hiroshi Teramoto, Asahi Tsuchida, Yutaro Kabata, Kenji Kondo, KatsusukeNabeshima, ShyūichiIzumiya, Mikito Toda, Tamiki Komatsuzaki
Dynamics Days Europe 2018, 03 Sep. 2018, English
[International presentation]

Fermi arcs for Weyl semimetals and line-node semimetals in topological insulator superlattice　　　　　　　　　　　　　　　
R. Itoh, K. Kondo
10th International School and Conference on Physics and Applications of Spin Phenomena in Solids (PASPS10), 06 Aug. 2018, English
[International presentation]

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　　　　　　　　　　　　　　　
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, 19 Mar. 2018, Japanese
[Domestic Conference]

トポロジカル絶縁体超格子におけるフェルミアーク　　　　　　　　　　　　　　　
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), 17 Mar. 2018, Japanese
[Domestic Conference]

An Arbitrary Order Effective Hamiltonian of Hexagonal Warping Effects of Dirac Cone　　　　　　　　　　　　　　　
K. Kondo, H. Teramoto
The 62nd Annual Conference on Magnetism and Magnetic Materials, 09 Nov. 2017, English
[International presentation]

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
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), 25 Aug. 2017, Japanese
25 Aug. 2017 - 25 Aug. 2017

Topological Spin Currents in Graphene Nanoribbons　　　　　　　　　　　　　　　
R. Itoh, K. Kondo
Spintech IX, 07 Jun. 2017, English
[International presentation]

Symmetric and Asymmetric Wave-guides for Multi-striped Orthogonal Photon-Photocarrier-Propagation Solar Cells (MOP3SC)　　　　　　　　　　　　　　　
A. Ishibashi, H. Kobayashi, N. Sawamura, K. Kondo, T. Kasai
2017 IEEE International Conference on Applied System Innovation (IEEE ICASI 2017), May 2017, English
[International presentation]

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　　　　　　　　　　　　　　　
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, 15 Mar. 2017, Japanese
[Domestic Conference]

グラフェンナノリボンと量子スピンホール相　　　　　　　　　　　　　　　
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, 14 Mar. 2017, Japanese
[Domestic Conference]

A Revisit of Quantum Spin Hall Effect in Graphene　　　　　　　　　　　　　　　
R. Itoh, K. Kondo
The 17th RIES-HOKUDAI INTERNATIONAL SYMPOSIUM on 柔, 13 Dec. 2016, English
[International presentation]

A Warping Effect of Dirac Cone by the Perturbation up to 5th Order under the Symmetry of C3v　　　　　　　　　　　　　　　
K. Kondo, H. Teramoto
The 61st Annual Conference on Magnetism and Magnetic Materials, 01 Nov. 2016, English
[International presentation]

C_3v_対称性の下での5次摂動によるDirac Coneのワーピング　　　　　　　　　　　　　　　
近藤 憲治, 寺本 央
2016年日本物理学会秋季大会, 13 Sep. 2016, Japanese
[Domestic Conference]

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　　　　　　　　　　　　　　　
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, 21 Mar. 2016, Japanese
[Domestic Conference]

The Warping Effect of Dirac Cone by the Perturbation up to 5th Order under the Symmetry of C_3v.
Kondo Kenji, Teramoto Hiroshi
Meeting Abstracts of the Physical Society of Japan, 2016, The Physical Society of Japan, Japanese
2016 - 2016, <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　　　　　　　　　　　　　　　
近藤 憲治
日本物理学会秋季大会2015, 16 Sep. 2015, Japanese
[Domestic Conference]

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　　　　　　　　　　　　　　　
近藤 憲治
第76回応用物理学会秋季学術講演会, 13 Sep. 2015, Japanese
[Domestic Conference]

Spin filtering in Double Quantum Dots Aharonov-Bohm Ring under Cubic Rashba Spin Orbit Interaction　　　　　　　　　　　　　　　
Kenji Kondo
The 20th International Conference on Magnetism, 06 Jul. 2015, English
[International presentation]

AC impedance characteristics of Co/Alq3/Ni75Fe25 junctions　　　　　　　　　　　　　　　
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, 17 Dec. 2014, English
[International presentation]

Validity of the Free Electron Model for Two-Dimensional Electrodes　　　　　　　　　　　　　　　
Kenji Kondo
2014 MRS Fall Meeting, Dec. 2014, English
[International presentation]

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　　　　　　　　　　　　　　　
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, 17 Sep. 2014, Japanese
[Domestic Conference]

Ni75Fe25/Alq3/Co接合における交流インピーダンス特性　　　　　　　　　　　　　　　
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, 17 Sep. 2014, Japanese
[Domestic Conference]

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　　　　　　　　　　　　　　　
近藤 憲治
2014年日本物理学会秋季大会, 07 Sep. 2014, Japanese
[Domestic Conference]

Negative Magnetoresistance in Ferromagnet/Semiconductor/Ferromagnet Structures with Cubic Dresselhaus Spin-Orbit-Interaction　　　　　　　　　　　　　　　
Kenji Kondo
The 14th RIES-Hokudai International Symposium, 11 Dec. 2013, English
[International presentation]

Fabrication of Ni-based Nanoscale Junctions Utilizing Thin-Film Edges and Their Structural and Electrical Properties　　　　　　　　　　　　　　　
H. Kaiju, K. Kondo, M. Ishimaru, Y. Hirotsu, A. Ishibashi
The 2013 Energy, Materials and Nanotechnology Fall Meeting, Dec. 2013, English
[International presentation]

Spin transport in normal metal/insulator/topological insulator coupled to ferromagnetic insulator structures　　　　　　　　　　　　　　　
Kenji Kondo
The 58th Annual Magnetism and Magnetic Materials Conference, Nov. 2013, English
[International presentation]

2次元金属電極における自由電子近似の妥当性　　　　　　　　　　　　　　　
近藤 憲治
日本物理学会秋季大会2013, Sep. 2013, Japanese
[Domestic Conference]

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　　　　　　　　　　　　　　　
近藤 憲治, 海住 英生, 石橋 晃
日本物理学会秋季大会2013, Sep. 2013, Japanese
[Domestic Conference]

Co/PENにおける面内磁気光学カー効果の回転磁場依存性　　　　　　　　　　　　　　　
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, Sep. 2013, Japanese
[Domestic Conference]

Co/Alq3/Ni75Fe25接合における電気・磁気・構造特性　　　　　　　　　　　　　　　
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, Sep. 2013, Japanese
[Domestic Conference]

外国語文献購読II　　　　　　　　　　　　　　　
北海道大学

量子デバイス物理学　　　　　　　　　　　　　　　
北海道大学

基礎物理学II（電磁気学と熱力学） （2006－2009年度）　　　　　　　　　　　　　　　
北海道大学

電子物性物理学 （トポロジカル物質の理論とスピントロニクス）　　　　　　　　　　　　　　　
北海道大学

全学教育科目（物理学III(電磁気学) 2005年度）　　　　　　　　　　　　　　　
北海道大学

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
科学研究費補助金(基盤研究(B))
Apr. 2017 - Mar. 2020
植村 哲也
分担者：近藤憲治
文部科学省, Competitive research funding

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
科学研究費補助金(基盤研究(B))
Apr. 2016 - Mar. 2020
笹倉 弘理
分担者：近藤憲治、熊野英和
文部科学省, Competitive research funding

トポロジカルな性質を持つ物質とその応用の研究
CSRN提案共同プロジェクト
Apr. 2016 - Mar. 2019
近藤 憲治
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), Principal investigator, Competitive research funding

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
科学研究費補助金(基盤研究(C))
2016 - 2019
近藤 憲治
文部科学省, Principal investigator, Competitive research funding

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
科学研究費補助金(基盤研究(C))
Apr. 2012 - Mar. 2015
近藤 憲治
文部科学省, 基盤研究(C), 北海道大学, Principal investigator, Competitive research funding, 24560001

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
科学研究費補助金(基盤研究(B))
2010 - 2012
石橋 晃, 近藤 憲治, 海住 英生
文部科学省, 基盤研究(B), 北海道大学, Coinvestigator not use grants, Competitive research funding, 22350077

スピン伝導の基礎理論構築と新規なデバイスの設計
科学研究費補助金(基盤研究(C))
2009 - 2011
近藤 憲治, 海住 英生
文部科学省, 基盤研究(C), 北海道大学, Principal investigator, Competitive research funding, 21560001

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　　　　　　　　　　　　　　　
若手育成研究費
Apr. 2003 - Mar. 2005
近藤 憲治
北海道大学電子科学研究所, Principal investigator, Competitive research funding

半導体レーザ及びその製造方法
Patent right, 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
特願平6-194951, 27 Jul. 1994
特開平7-297486, 10 Nov. 1995
特許第3277711号
15 Feb. 2002
200903022624077503

安定共振器を有する光学系
Patent right, 和田 裕之, 増田 久, 近藤 憲治, 岡 美智雄, ソニー株式会社
特願平9-268506, 01 Oct. 1997
特開平11-109426, 23 Apr. 1999
200903040487288630

レーザ共振器の寿命延長方法
Patent right, 近藤 憲治, 岡 美智雄, ソニー株式会社
特願平9-239248, 04 Sep. 1997
特開平11-087814, 30 Mar. 1999
200903010729572870

レーザ光発生装置
Patent right, 近藤 憲治, 岡 美智雄, ソニー株式会社
特願平9-228107, 25 Aug. 1997
特開平11-064904, 05 Mar. 1999
200903081768900995

光デバイス
Patent right, 近藤 憲治, ソニー株式会社
特願平6-071496, 15 Mar. 1994
特開平7-254756, 03 Oct. 1995
200903092546206154

多層膜中の導波光シミュレーション方法
Patent right, 近藤 憲治, ソニー株式会社
特願平5-226420, 19 Aug. 1993
特開平7-056031, 03 Mar. 1995
200903096770257738

半導体レーザーの駆動方法
Patent right, 岩本 浩治, 近藤 憲治, ソニー株式会社
特願平4-061097, 17 Feb. 1992
特開平5-226784, 03 Sep. 1993
200903023650796611

Laser beam generating apparatus　　　　　　　　　　　　　　　
Patent right, KONDO Kenji
特願US-543136
特許US-6404786

II-VI semiconductor laser with different guide layers　　　　　　　　　　　　　　　
Patent right, KONDO Kenji
特願US-394742
特許US-5572539

Oct. 2021 - Oct. 2021
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」