Papers

  1. K. Baba, K. Noro, Y. Kozuka, T. Kumasaka, M. Shinozaki, M. Kawasaki, T. Otsuka
    "Formation of multiple quantum dots in ZnO heterostructures"
    (arXiv:2504.03049)
  2. K. Noro, M. Shinozaki, Y. Kozuka, K. Matsumura, Y. Fujiwara, T. Kumasaka, A. Tsukazaki, M. Kawasaki, T. Otsuka
    "Charge sensing of few-electron ZnO double quantum dots probed by radio-frequency reflectometry"
    (arXiv:2501.04949)
  3. K. Masuda, T. Scheike, H. Sukegawa, Y. Kozuka, S. Mitani, Y. Miura
    "Theory for tunnel magnetoresistance oscillation"
    (arXiv:2406.07919)
  4. Y. Kozuka, S. Tsuda, T. D. Phan, K. Yaji, J. Uzuhashi, T. Ohkubo, T. Hiroto, T. Makino, J. Falson, A. Tsukazaki, M. Kawasaki
    "Structural, optical, and electronic properties of MgxZn1-xO (0 ≤ x ≤ 0.38) films pseudomorphically grown on Zn-polar ZnO substrates"
    Materials Today Quantum 6, 100036 (2025)
    DOI: 10.1016/j.mtquan.2025.100036
  5. K. Noro, Y. Kozuka, K. Matsumura, T. Kumasaka, Y. Fujiwara, A. Tsukazaki, M. Kawasaki, T. Otsuka
    "Parity-independent Kondo effect of correlated electrons in electrostatically defined ZnO quantum dots"
    Nature Communications 15, 9556 (2024)
    DOI: 10.1038/s41467-024-53890-2
    (arXiv:2311.12508)
  6. T. Itoh, Y. Kozuka, T. Hirai, K. Uchida
    "Enhancement of transverse thermoelectric conversion by interface-induced spin current in ferromagnetic metal/nonmagnetic insulator hybrid-structure"
    Advanced Functional Materials 34, 2409557 (2024)
    DOI: 0.1002/adfm.202409557
  7. Y. Ishii, Y. Yamasaki, Y. Kozuka, J. Lustikova, Y. Nii, Y. Onose, Y. Yokoyama, M. Mizumaki, J. Adachi, H. Nakao, T. Arima, Y. Wakabayashi
    "Microscopic evaluation of spin and orbital moment in ferromagnetic resonance"
    Scientific Reports 14, 15504 (2024)
    DOI: 10.1038/s41598-024-66139-1
  8. N. Abe, Y. Hano, H. Ishizuka, Y. Kozuka, T. Tadano, Y. Tsujimoto, K. Yamaura, S. Ishiwata, J. Fujioka
    "Large anomalous Hall effect in spin fluctuating devil’s staircase"
    npj Quantum Materials 9, 41 (2024)
    DOI: 10.1038/s41535-024-00653-3
  9. H. Tsurusawa, J. Uzuhashi, Y. Kozuka, K. Kimoto, T. Ohkubo
    "Robust preparation of sub-20-nm-thin lamellae for aberration-corrected electron microscopy"
    Small Methods 2301425 (2024)
    DOI: 10.1002/smtd.202301425
  10. Y. Kozuka, T. T. Sasaki, T. Tadano, J. Fujioka
    "Epitaxy and transport properties of alkali-earth palladate thin films"
    Science and Technology of Advanced Materials 24, 2265431 (2023)
    DOI: 10.1080/14686996.2023.2265431
  11. K. Kazama, M. Sakano, K. Yamagami, T. Ohkochi, K. Ishizaka, T. Tadano, Y. Kozuka, H. Yoshizawa, Y. Tsujimoto, K. Yamaura, J. Fujioka
    "Charge transport and thermopower in the electron-doped narrow gap semiconductor Ca1-xLaxPd3O4"
    Physical Review Materials 7, 085402-1-6 (2023)
    DOI: 10.1103/PhysRevMaterials.7.085402
  12. Y. Ishii, Y. Kozuka, Y. Yamasaki, H. Nakao
    "Development of multi-scale soft X-ray diffraction microscope for observing spin textures"
    JPS Conference Proceedings 38, 11190 (2023)
    DOI: 10.7566/JPSCP.38.011190
  13. Saikat Das, S. Sugimoto, V. Kushwaha, Y. Kozuka, S. Kasai
    "Observation of charge-to-spin conversion with giant efficiency at Ni0.8Fe0.2/Bi2WO6 interface"
    APL Materials 11, 41113 (2023)
    DOI: 10.1063/5.0142695
    (arXiv:2304.02751)
  14. S. Isogami, M. Ohtake, Y. Kozuka, Y. K. Takahashi
    "Wide modulation of coercive fields in Mn4N ferrimagnetic thin films caused dominantly by dislocation microstructures"
    Journal of Magnetism and Magnetic Materials 560, 169642 (2022)
    DOI: 10.1016/j.jmmm.2022.169642
  15. V. Niaouris, M. V. Durnev, X. Linpeng, M. L. K. Viitaniemi, C. Zimmermann, Aswin Vishnuradhan, Y. Kozuka, M. Kawasaki, K.-M. C. Fu
    "Ensemble spin relaxation of shallow donor qubits in ZnO"
    Physical Review B 105, 195202 (2022)
    DOI: 10.1103/PhysRevB.105.195202
    (arXiv:2111.11564)
  16. J. Falson, I. Sodemann, B. Skinner, D. Tabrea, Y. Kozuka, A. Tsukazaki, M. Kawasaki, K. von Klitzing, J. H. Smet
    "Competing correlated states around the zero-field Wigner crystallization transition of electrons in two dimensions"
    Nature Materials 21, 311-316 (2022)
    DOI: 10.1038/s41563-021-01166-1
    (arXiv:2103.16586)
  17. S. Isogami, N. Rajamanickam, Y. Kozuka, Y. K. Takahashi
    "Efficient current-driven magnetization switching owing to isotropic magnetism in a highly symmetric 111-oriented Mn4N epitaxial single layer"
    AIP Advances 11, 105314-1-6 (2021)
    DOI: 10.1063/5.0062253
  18. S. Iwakiri, S. Sugimoto, Y. Niimi, Y. Kozuka, Y. K. Takahashi, S. Kasai, K. Kobayashi
    "Negative correlation between the linear and the nonlinear conductance in magnetic tunnel junctions"
    Physical Review B 103, 245427-1-5 (2021)
    DOI: 10.1103/PhysRevB.103.245427
    (arXiv:2106.11274 )
  19. Y. Kozuka, S. Isogami, K. Masuda, Y. Miura, Saikat Das, J. Fujioka, T. Ohkubo, S. Kasai
    "Observation of nonlinear spin-charge conversion in the thin film of nominally centrosymmetric Dirac semimetal SrIrO3 at room temperature"
    Physical Review Letters 126, 236801-1-6 (2021)
    DOI: 10.1103/PhysRevLett.126.236801
    (arXiv:2105.03574)
  20. D. Maryenko, M. Kawamura, A. Ernst, V. K. Dugaev, E. Ya. Sherman, M. Kriener, M. S. Bahramy, Y. Kozuka, M. Kawasaki
    "Interplay of spin-orbit coupling and Coulomb interaction in ZnO-based electron system"
    Nature Communications 12, 3180 (2021)
    DOI: 10.1038/s41467-021-23483-4
    (arXiv:2010.02461)
  21. Saikat Das, T. Ohkubo, S. Kasai, Y. Kozuka
    "Deterministic influence of substrate-induced oxygen vacancy diffusion on Bi2WO6 thin film growth"
    Crystal Growth & Design 21, 625-630 (2021)
    DOI: 10.1021/acs.cgd.0c01428
    (arXiv:2101.10559)
  22. D. Tabrea, I. A. Dmitriev, S. I. Dorozhkin, B. P. Gorshunov, A. V. Boris, Y. Kozuka, A. Tsukazaki, M. Kawasaki, K. von Klitzing, J. Falson
    "Microwave response of interacting oxide two-dimensional electron systems"
    Physical Review B 102, 115432-1-8 (2020)
    DOI: 10.1103/PhysRevB.102.115432
    (arXiv:2006.13627)
  23. S. Sugimoto, S. Iwakiri, Y. Kozuka, Y. Takahashi, Y. Niimi, K. Kobayashi, S. Kasai
    "Multiple modes of a single spin torque oscillator under the non-linear region"
    AIP Advances 10, 75115-1-6 (2020)
    DOI: 10.1063/5.0013105
    (arXiv:2005.07836)
  24. M. Kawamura, M. Mogi, R. Yoshimi, A. Tsukazaki, Y. Kozuka, K. S. Takahashi, M. Kawasaki, Y. Tokura
    "Current scaling of the topological quantum phase transition between a quantum anomalous Hall insulator and a trivial insulator"
    Physical Review B 102, 041301(R)-1-6 (2020)
    DOI: 10.1103/PhysRevB.102.041301
    (arXiv:2007.01197)
  25. S. Iwakiri, S. Sugimoto, Y. Niimi, K. Kobayashi, Y. Kozuka, Y. K. Takahashi, S. Kasai
    "Generation of multipeak spectrum of spin torque oscillator in non-linear regime"
    Applied Physics Letters 117, 22406-1-4 (2020)
    DOI: 10.1063/5.0013102
    (arXiv:2005.07434)
  26. K. Tanaka, J. Falson, Y. Kozuka, M. Uchida, D. Maryenko, J. T. Ye, Y. Iwasa, A. Tsukazaki, J. H. Smet, M. Kawasaki
    "Ballistic transport in periodically modulated MgZnO/ZnO two-dimensional electron systems"
    Applied Physics Letters 115, 153101-1-4 (2019)
    DOI: 10.1063/1.5121005
  27. M. Uchida, M. Ide, M. Kawamura, K. S. Takahashi, Y. Kozuka, Y. Tokura, M. Kawasaki
    "Anomalous enhancement of upper critical field in Sr2RuO4 thin films"
    Physical Review B 99, 161111(R) (2019)
    DOI: 10.1103/PhysRevB.99.161111
    (arXiv:1903.08630)
  28. H. Hou, Y. Kozuka, Jun-Wei Liao, L. W. Smith, D. Kos, J. P. Griffiths, J. Falson, A. Tsukazaki, M. Kawasaki, C. J. B. Ford
    "Quantized conductance of one-dimensional strongly correlated electrons in an oxide heterostructure"
    Physical Review B 99, 121302(R)-1-6 (2019)
    DOI: 10.1103/PhysRevB.99.121302
    (arXiv:1903.03476)
  29. X. Linpeng, M. L. K. Viitaniemi, Aswin Vishnuradhan, Y. Kozuka, C. Johnson, M. Kawasaki, K.-M. C. Fu
    "Coherence properties of shallow donor qubits in ZnO"
    Physical Review Applied 10, 064061-1-9 (2018)
    DOI: 10.1103/PhysRevApplied.10.064061
    (arXiv:1802.03483)
  30. Y. Kozuka, A. Sakaguchi, J. Falson, A. Tsukazaki, M. Kawasaki
    "Andreev reflection at the interface with an oxide in the quantum Hall regime"
    Journal of the Physical Society of Japan 87, 124712-1-7 (2018)
    DOI: 10.7566/JPSJ.87.124712
    (arXiv:1810.08198)
  31. M. Kawamura, M. Mogi, R. Yoshimi, A. Tsukazaki, Y. Kozuka, K. S. Takahashi, M. Kawasaki, Y. Tokura
    "Topological quantum phase transition in magnetic topological insulator upon magnetization rotation"
    Physical Review B 98, 140404(R)-1-5 (2018)
    DOI: 10.1103/PhysRevB.98.140404
    (arXiv:1808.08930)
  32. D. Maryenko, A. McCollam, J. Falson, Y. Kozuka, J. Bruin, U. Zeitler, M. Kawasaki
    "Composite fermion liquid to Wigner solid transition in the lowest Landau level of zinc oxide"
    Nature Communications 9, 4356 (2018)
    DOI: 10.1038/s41467-018-06834-6
    (arXiv:1707.08406)
  33. R. Nishino, Y. Kozuka, F. Kagawa, M. Uchida, M. Kawasaki
    "Ferroelectric field control of charge density in oxide films with polarization reversal by electric double layer"
    Applied Physics Letters 113, 143501-1-4 (2018)
    DOI: 10.1063/1.5047558
  34. J. Falson, D. Tabrea, D. Zhang, I. Sodemann, Y. Kozuka, A. Tsukazaki, M. Kawasaki, K. von Klitzing, J. H. Smet
    "A cascade of phase transitions in an orbitally mixed half-filled Landau level"
    Science Advances 4, eaat8742 (2018)
    DOI: 10.1126/sciadv.aat8742
    (arXiv:1804.04565)
  35. S. Nishihaya, M. Uchida, Y. nakazawa, K. Akiba, M. Kriener, Y. Kozuka, A. miyake, Y. Taguchi, M. Tokunaka, M. Kawasaki
    "Negative magnetoresistance suppressed through a topological phase transition in (Cd1-xZnx)3As2 thin films "
    (arXiv:1806.02302)
  36. S. Nishihaya, M. Uchida, Y. Nakazawa, M. Kriener, Y. Kozuka, Y. Taguchi, M. Kawasaki
    "Gate-tuned quantum Hall states in Dirac semimetal (Cd1−xZnx)3As2"
    Science Advances 4, eaar5668 (2018)
    DOI: 10.1126/sciadv.aar5668
    (arXiv:1805.07572)
  37. Y. Nakazawa, M. Uchida, S. Nishihaya, M. Kriener, Y. Kozuka, Y. Taguchi, M. Kawasaki
    "Structural characterization of high-mobility Cd3As2 films crystallized on SrTiO3"
    Scientific Reports 8, 2244 (2018)
    DOI: 10.1038/s41598-018-20758-7
    (arXiv:1804.06312)
  38. R. Nishino, Y. Kozuka, M. Uchida, F. Kagawa, M. Kawasaki
    "Electrical conduction on the surface of ferroelectric PbTiO3 thin film induced by electrolyte gating"
    Applied Physics Letters 112, 051602-1-4 (2018)
    DOI: 10.1063/1.5010391
  39. T. C. Fujita, Y. Kozuka, J. Matsuno, M. Uchida, A. Tsukazaki, T. Arima, M. Kawasaki
    "All-in-all-out magnetic domain inversion in Tb2Ir2O7 with molecular fields antiparallel to external fields"
    Physical Review Materials 2, 011402(R)-1-5 (2018)
    DOI: 10.1103/PhysRevMaterials.2.011402
  40. Y. Ohuchi, J. Matsuno, N. Ogawa, Y. Kozuka, M. Uchida, Y. Tokura, M. Kawasaki
    "Electric-field control of anomalous and topological Hall effects in oxide bilayer thin films"
    Nature Communications 9, 213 (2018)
    DOI: 10.1038/s41467-017-02629-3
    (arXiv:1801.06272 )
  41. N. Kanazawa , J. S. White, H. M. Rønnow, C. D. Dewhurst, D. Morikawa, K. Shibata, T. Arima, F. Kagawa, A. Tsukazaki, Y. Kozuka, M. Ichikawa, M. Kawasaki, Y. Tokura
    "Topological spin-hedgehog crystals of a chiral magnet as engineered with magnetic anisotropy"
    Physical Review B 96, 220414(R)-1-6 (2017)
    DOI: 10.1103/PhysRevB.96.220414
  42. M. Uchida, Y. Nakazawa, S. Nishihaya, K. Akiba, M. Kriener, Y. Kozuka, A. Miyske, Y. Taguchi, M. Tokunaga, N. Nagaosa, Y. Tokura, M. Kawasaki
    "Quantum Hall states observed in thin films of Dirac semimetal Cd3As2"
    Nature Communications 8, 2274 (2017)
    DOI: 10.1038/s41467-017-02423-1
    (arXiv:1712.09490)
  43. Y. Kozuka, T. C. Fujita, M. Uchida, T. Nojima, A. Tsukazaki, J. Matsuno, T. Arima, M. Kawasaki
    "Visualizing ferroic domains in an all-in-all-out antiferromagnet thin film"
    Physical Review B 96, 224417-1-5 (2017)
    DOI: 10.1103/PhysRevB.96.224417
  44. Q. Shi, J. Falson, M. A. Zudov, Y. Kozuka, A. Tsukazaki, M. Kawasaki, J. Smet
    "Nonlinear response of a MgZnO/ZnO heterostructure close to zero bias"
    Physical Review B 96, 125401-1-4 (2017)
    DOI: 10.1103/PhysRevB.96.125401
    (arXiv:1708.09841)
  45. D. Maryenko, A. S. Mishchenko, M. S. Bahramy, A. Ernst, J. Falson, Y. Kozuka, A. Tsukazaki, N. Nagaosa, M. Kawasaki
    "Observation of anomalous Hall effect in a non-magnetic two-dimensional electron system"
    Nature Communications 8, 14777 (2017)
    DOI: 10.1038/ncomms14777
  46. M. Mogi, M. Kawamura, R. Yoshimi, A. Tsukazaki, Y. Kozuka, N. Shirakawa, K. S. Takahashi, M. Kawasaki, Y. Tokura
    "A magnetic heterostructure of topological insulators as a candidate for an axion insulator"
    Nature Materials 16, 516-521 (2017)
    DOI: 10.1038/nmat4855
  47. Q. Shi, M. A. Zudov, J. Falson, Y. Kozuka, A. Tsukazaki, M. Kawasaki, K. von Klitzing, J. Smet
    "Hall field-induced resistance oscillations in MgZnO/ZnO heterostructures"
    Physical Review B 95, 041411(R)-1-4 (2017)
    DOI: 10.1103/PhysRevB.95.041411
    (arXiv:1702.02557)
  48. Aswin Vishnuradhan, Y. Kozuka, M. Uchida, J. Falson, A. Tsukazaki, M. Kawasaki
    "Alloy disorder modulated electron transport at MgxZn1-xO/ZnO heterointerface"
    AIP Advances 7, 15029-1-7 (2017)
    DOI: 10.1063/1.4974462
  49. N. Kanazawa, J. S. White, H. M. Ronnow, C. D. Dewhurst, Y. Fujishiro, A. Tsukazaki, Y. Kozuka, M. Kawasaki, M. Ichikawa, F. Kagawa, and Y. Tokura
    "Direct observation of the anisotropic magnetic field response of the spin helix in FeGe thin film"
    Physical Review B 94, 184432-1-7 (2016)
    DOI: 10.1103/PhysRevB.94.184432
  50. S. Nishihaya, M. Uchida, Y. Kozuka, Y. Iwasa, M. Kawasaki
    "Evolution of insulator-metal phase transitions in epitaxial tungsten oxide films during electrolyte-gating"
    ACS Applied Materials & Interfaces 8, 22330-22336 (2016)
    DOI: 10.1021/acsami.6b06593
    (arXiv:1608.03357)
  51. J. Falson, Y. Kozuka, M. Uchida, J. H. Smet, T. Arima, A. Tsukazaki, M. Kawasaki
    "MgZnO/ZnO heterostructures with electron mobility exceeding 1× 106 cm2/Vs"
    Scientific Reports 6, 26598 (2016)
    DOI: 10.1038/srep26598
  52. Y. Matsubara, K. S. Takahashi, M. S. Bahramy, Y. Kozuka, D. Maryenko, J. Falson, A. Tsukazaki, Y. Tokura, M. Kawasaki
    "Observation of the quantum Hall effect in δ-doped SrTiO3"
    Nature Communications 7, 11631 (2016)
    DOI: 10.1038/ncomms11631
  53. T. C. Fujita, M. Uchida, Y. Kozuka, W. Sano, A. Tsukazaki, T. Arima, M. Kawasaki
    "All-in-all-out magnetic domain wall conduction in pyrochlore iridate heterointerface"
    Physical Review B 93, 064419-1-6 (2016)
    DOI: 10.1103/PhysRevB.93.064419
    (arXiv:1602.00450)
  54. M. Uchida, K. Ohba, Y. Ohuchi, Y. Kozuka, M. Kawasaki
    "Epitaxially stabilized oxide composed of twisted triangular-lattice layers"
    Chemistry of Materials 28, 1165-1169 (2016)
    DOI: 10.1021/acs.chemmater.5b04702
    (arXiv:1602.08192)
  55. M. Ito, M. Uchida, Y. Kozuka, K. S. Takahashi, M. Kawasaki
    "Effective carrier doping and metallization in LaxSr2−x−yBayIrO4−δ thin films"
    Physical Review B 93, 045139-1-5 (2016)
    DOI: 10.1103/PhysRevB.93.045139
    (arXiv:1601.07964)
  56. T. C. Fujita, M. Uchida, Y. Kozuka, S. Ogawa, A. Tsukazaki, T. Arima, M. Kawasaki
    "All-in-all-out magnetic domain size in pyrochlore iridate thin films as probed by local magnetotransport"
    Applied Physics Letters 108, 022402-1-5 (2016)
    DOI: 10.1063/1.4939742
    (arXiv:1601.02710)
  57. D. F. Kärcher, A. V. Shchepetilnikov, Yu. A. Nefyodov, J. Falson, I. A. Dmitriev, Y. Kozuka, D. Maryenko, A. Tsukazaki, S. I. Dorozhkin, I. V. Kukushkin, M. Kawasaki, J. H. Smet
    "Observation of microwave induced resistance oscillations in MgZnO/ZnO heterostructures"
    Physical Review B 93, 041410(R)-1-5 (2016)
    DOI: 10.1103/PhysRevB.93.041410
  58. S. Seki, T. Ideue, M. Kubota, Y. Kozuka, R. Takagi, M. Nakamura, Y. Kaneko, M. Kawasaki, Y. Tokura
    "Thermal generation of spin current in an antiferromagnet"
    Physical Review Letters 115, 266601-1-5 (2015)
    DOI: 10.1103/PhysRevLett.115.266601
    (arXiv:1508.02555)
  59. T. Murata, Y. Kozuka, M. Uchida, M. Kawasaki
    "Magnetic properties of spin frustrated spinel ZnFe2O4/ZnCr2O4 superlattices"
    Journal of Applied Physics 118, 193901-1-5 (2015)
    DOI: 10.1063/1.4935818
  60. M. Mogi, R. Yoshimi, A. Tsukazaki, K. Yasuda, Y. Kozuka, K. S. Takahashi, M. Kawasaki, Y. Tokura
    "Magnetic modulation doping in topological insulators toward higher-temperature quantum anomalous Hall effect"
    Applied Physics Letters 107, 182401-1-5 (2015)
    DOI: 10.1063/1.4935075
    (arXiv:1511.01724 )
  61. D. Maryenko, J. Falson, M. S. Bahramy, I. A. Dmitriev, Y. Kozuka, A. Tsukazaki, M. Kawasaki
    "Spin-selective electron quantum transport in non-magnetic MgZnO/ZnO-heterostructures"
    Physical Review Letters 115, 197601-1-5 (2015)
    DOI: 10.1103/PhysRevLett.115.197601
  62. T. Yokouchi, N. Kanazawa, A. Tsukazaki, Y. Kozuka, A. Kikkawa, Y. Taguchi, M. Kawasaki, M. Ichikawa, F. Kagawa, Y. Tokura
    "Formation of in-plane skyrmions in epitaxial MnSi thin films as revealed by planar Hall effect"
    Journal of the Physical Society of Japan 84, 104708-1-5 (2015)
    DOI: 10.7566/JPSJ.84.104708
    (arXiv:1506.04821)
  63. J. Falson, Y. Kozuka, J. H. Smet, T. Arima, A. Tsukazaki, M. Kawasaki
    "Electron scattering times in ZnO based polar heterostructures"
    Applied Physics Letters 107, 082102-1-4 (2015)
    DOI: 10.1063/1.4929381
  64. M. Uchida, W. Sano, K. S. Takahashi, T. Koretsune, Y. Kozuka, R. Arita, Y. Tokura, M. Kawasaki
    "Field-direction control of the type of charge carriers in nonsymmorphic IrO2"
    Physical Review B 91, 241119(R)-1-5 (2015)
    DOI: 10.1103/PhysRevB.91.241119
    (arXiv:1507.00806)
  65. E. Majima, Y. Kozuka, M. Uchida, M. Nakamura, M. Kawasaki
    "Band alignment and photovoltaic effect of epitaxial α-PbO thin films"
    Applied Physics Express 8, 074001-1-4 (2015)
    DOI: 10.7567/APEX.8.074001
  66. Y. Ohuchi, Y. Kozuka, M. Uchida, K. Ueno, A. Tsukazaki, M. Kawasaki
    "Topological Hall effect in thin films of the Heisenberg ferromagnet EuO"
    Physical Review B 91, 245115-1-5 (2015)
    DOI: 10.1103/PhysRevB.91.245115
  67. T. C. Fujita, Y. Kozuka, M. Uchida, A. Tsukazaki, T. Arima, M. Kawasaki
    "Odd-parity magnetoresistance in pyrochlore iridate thin films with broken time-reversal symmetry"
    Scientific Reports 5, 9711 (2015)
    DOI: 10.1038/srep09711
    (arXiv:1508.01318)
  68. R. Yoshimi, A. Tsukazaki, Y. Kozuka, J. Falson, K. S. Takahashi, J. G. Checkelsky, N. Nagaosa, M. Kawasaki, Y. Tokura
    "Quantum Hall effect on top and bottom surface states of topological insulator (Bi1-xSbx)2Te2 films"
    Nature Communications 6, 6627 (2015)
    DOI: 10.1038/ncomms7627
    (arXiv:1409.3326)
  69. J. Falson, D. Maryenko, B. Friess, D. Zhang, Y. Kozuka, A. Tsukazaki, J. H. Smet, M. Kawasaki
    "Even-denominator fractional quantum Hall physics in ZnO"
    Nature Physics 11, 347-351 (2015)
    DOI: 10.1038/nphys3259
  70. V. V. Solovyev, A. B. Van'kov, I. V. Kukushkin, J. Falson, D. Zhang, D. Maryenko, Y. Kozuka, A. Tsukazaki, J. H. Smet, M. Kawasaki
    "Optical probing of MgZnO/ZnO heterointerface confinement potential energy levels"
    Applied Physics Letters 106, 082102-1-4 (2015)
    DOI: 10.1063/1.4913313
  71. V. E. Kozlov, A. B. Van'kov, S. I. Gubarev, I. V. Kukushkin, V. V. Solovyev, J. Falson, D. Maryenko, Y. Kozuka, A. Tsukazaki, M. Kawasaki, J. H. Smet
    "Microwave magnetoplasma resonances of two-dimensional electrons in MgZnO/ZnO heterojunctions"
    Physical Review B 91, 085304-1-6 (2015)
    DOI: 10.1103/PhysRevB.91.085304
  72. N. Kanazawa, M. Kubota, A. Tsukazaki, Y. Kozuka, K. S. Takahashi, M. Kawasaki, M. Ichikawa, F. Kagawa, Y. Tokura
    "Discretized topological Hall effect emerging from skyrmions in constricted geometry"
    Physical Review B 91, 041122(R)-1-5 (2015)
    DOI: 10.1103/PhysRevB.91.041122
    (arXiv:1501.03290 )
  73. M. Uchida, J. Falson, Y. Segawa, Y. Kozuka, A. Tsukazaki, M. Kawasaki
    "Calibration and control of in-plane Mg doping distribution in MgxZn1-xO/ZnO heterostructures grown by molecular beam epitaxy"
    Japanese Journal of Applied Physics 54, 028004-1-3 (2015)
    DOI: 10.7567/JJAP.54.028004
  74. D. Maryenko, J. Falson, Y. Kozuka, A. Tsukazaki, M. Kawasaki
    "Polarization-dependent Landau level crossing in a two-dimensional electron system in a MgZnO/ZnO heterostructure"
    Physical Review B 90, 245303-1-5 (2014)
    DOI: 10.1103/PhysRevB.90.245303
    (arXiv:1409.7761)
  75. T. Tambo, J. Falson, D. Maryenko, Y. Kozuka, A. Tsukazaki, M. Kawasaki
    "Air-gap gating of MgZnO/ZnO heterostructures"
    Journal of Applied Physics 116, 084310-1-5 (2014)
    DOI: 10.1063/1.4894155
  76. J. G. Checkelsky, R. Yoshimi, A. Tsukazaki, K. S. Takahashi, Y. Kozuka, J. Falson, M. Kawasaki, Y. Tokura
    "Trajectory of anomalous Hall effect toward the quantized state in a ferromagnetic topological insulator"
    Nature Physics 10, 731-736 (2014)
    DOI: 10.1038/nphys3053
    (arXiv:1406.7450 )
  77. K. Imasaka, J. Falson, Y. Kozuka, A. Tsukazaki, M. Kawasaki
    "Spontaneous polarization driven Mg concentration profile reconstruction in MgZnO/ZnO heterostructures"
    Applied Physics Letters 104, 242112-1-5 (2014)
    DOI: 10.1063/1.4884383
  78. M. Ito, Y. Matsubara, Y. Kozuka, K. S. Takahashi, F. Kagawa, J. T. Ye, Y. Iwasa, K. Ueno, Y. Tokura, M. Kawasaki
    "Electric double layer transistor with ferroelectric BaTiO3 channels"
    Applied Physics Letters 104, 222101-1-4 (2014)
    DOI: 10.1063/1.4881059
  79. Y. Ohuchi, Y. Kozuka, N. Rezaei, M. S. Bahramy, R. Arita, K. Ueno, A. Tsukazaki, M. Kawasaki
    "Photo-induced sign inversion of the anomalous Hall effect in EuO thin films"
    Physical Review B 89, 121114(R)-1-5 (2014)
    DOI: 10.1103/PhysRevB.89.121114
  80. M. Brasse, S. M. Sauther, J. Falson, Y. Kozuka, A. Tsukazaki, Ch. Heyn, M. A. Wilde, M. Kawasaki, D. Grundler
    "Enhanced quantum oscillatory magnetization and non-equilibrium currents in an interacting two-dimensional electron system in MgZnO/ZnO with repulsive scatterers"
    Physical Review B 89, 075307-1-5 (2014)
    DOI: 10.1103/PhysRevB.89.075307
    (arXiv:1307.3504 )
  81. T. Yokouchi, N. Kanazawa, A. Tsukazaki, Y. Kozuka, M. Kawasaki, M. Ichikawa, F. Kagawa, Y. Tokura
    "Stability of two-dimensional skyrmions in thin films of Mn1-xFexSi as investigated by topological Hall effect"
    Physical Review B 89, 064416-1-6 (2014)
    DOI: 10.1103/PhysRevB.89.064416
  82. Y. Kozuka, A. Tsukazaki, M. Kawasaki
    "Challenges and opportunities of ZnO-related single crystalline heterostructures"
    Applied Physics Reviews 1, 011303-1-18 (2014)
    DOI: 10.1063/1.4853535
    (arXiv:1311.5088)
  83. V. E. Kozlov, A. B. Van'kov, S. I. Gubarev, I. V. Kukushkin, J. Falson, D. Maryenko, Y. Kozuka, A. Tsukazaki, M. Kawasaki, J. H. Smet
    "Observation of plasma and magnetoplasma resonances of two-dimensional electrons in a single MgZnO/ZnO heterojunction"
    JETP Letters 98, 223-226 (2013)
    DOI: 10.1134/S0021364013170074
  84. Y. Kozuka, S. Teraoka, J. Falson, A. Oiwa, A. Tsukazaki, S. Tarucha, M. Kawasaki
    "Rashba spin-orbit interaction in a MgxZn1-xO/ZnO two-dimensional electron gas studied by electrically detected electron spin resonance"
    Physical Review B 87, 205411-1-5 (2013)
    DOI: 10.1103/PhysRevB.87.205411
  85. T. C. Fujita, Y. Kozuka, H. Seki, M. Kawasaki
    "Charge-spin-coupled electrical transport properties in EuMoO3/SrTiO3 superlattices"
    Physical Review B 87, 205402-1-8 (2013)
    DOI: 10.1103/PhysRevB.87.205402
  86. Y. Kasahara, Y. Oshima, J. Falson, Y. Kozuka, A. Tsukazaki, M. Kawasaki, Y. Iwasa
    "Correlation-enhanced effective mass of two-dimensional electrons in MgxZn1-xO/ZnO heterostructures"
    Physical Review Letters 109, 246401-1-5 (2012)
    DOI: 10.1103/PhysRevLett.109.246401
  87. Y. Kozuka, H. Seki, T. C. Fujita, S. Chakraverty, K. Yoshimatsu, H. Kumigashira, M. Oshima, M. S. Bahramy, R. Arita, M. Kawasaki
    "Epitaxially stabilized EuMoO3: A new itinerant ferromagnet"
    Chemistry of Materials 24, 3746-3750 (2012)
    DOI: 10.1021/cm302231k
    (arXiv:1209.2032)
  88. Y. Kozuka, J. Falson, Y. Segawa, T. Makino, A. Tsukazaki, M. Kawasaki
    "Precise calibration of Mg concentration in MgxZn1-xO thin films grown on ZnO substrates"
    Journal of Applied Physics 112, 043515-1-5 (2012)
    DOI: 10.1063/1.4748306
    (arXiv:1208.2074)
  89. M. Kim, Y. Kozuka, C. Bell, Y. Hikita, H. Y. Hwang
    "Intrinsic spin-orbit coupling in superconducting δ-doped SrTiO3 heterostructures"
    Physical Review B 86, 085121-1-6 (2012)
    DOI: 10.1103/PhysRevB.86.085121
    (arXiv:1106.5193)
  90. T. Makino, F. Liu, T. Yamasaki, Y. Kozuka, K. Ueno, A. Tsukazaki, T. Fukumura, Y. Kong, M. Kawasaki
    "Ultrafast optical control of magnetization in EuO thin films"
    Physical Review B 86, 064403-1-5 (2012)
    DOI: 10.1103/PhysRevB.86.064403
    (arXiv:1207.6686)
  91. D. Maryenko, J. Falson, Y. Kozuka, A. Tsukazaki, M. Onoda, H. Aoki, M. Kawasaki
    "Temperature dependent magnetotransport around ν = 1/2 in ZnO heterostructures"
    Physical Review Letters 108, 186803-1-5 (2012)
    DOI: 10.1103/PhysRevLett.108.186803
    (arXiv:1203.3349)
  92. Y. Kozuka, A. Tsukazaki, D. Maryenko, J. Falson, C. Bell, M. Kim, Y. Hikita, H. Y. Hwang, M. Kawasaki
    "Single-valley quantum Hall ferromagnet in a dilute MgxZn1-xO/ZnO strongly correlated two-dimensional electron system"
    Physical Review B 85, 075302-1-5 (2012)
    DOI: 10.1103/PhysRevB.85.075302
  93. Y. Matsubara, T. Makino, H. Hiraga, C. Chen, S. Tsukimoto, K. Ueno, Y. Kozuka, Y. Ikuhara, M. Kawasaki
    "High crystallinity CuScO2 delafossite films exhibiting ultraviolet photoluminescence grown by vapor-liquid-solid tri-phase epitaxy"
    Applied Physics Express 5, 011201-1-3 (2012)
    DOI: 10.1143/APEX.5.011201
  94. S. Chakraverty, K. Yoshimatsu, Y. Kozuka, H. Kumigashira, M. Oshima, T. Makino, A. Ohtomo, M. Kawasaki
    "Magnetic and electronic properties of ordered double-perovskite La2VMnO6 thin films"
    Physical Review B 84, 132411-1-4 (2011)
    DOI: 10.1103/PhysRevB.84.132411
  95. M. Kim, C. Bell, Y. Kozuka, M. Kurita, Y. Hikita, H. Y. Hwang
    "Fermi surface and superconductivity in low-density high-mobility δ-doped SrTiO3"
    Physical Review Letters 107, 106801-1-4 (2011)
    DOI: 10.1103/PhysRevLett.107.106801
    (arXiv:1104.3388)
  96. J. Falson, D. Maryenko, Y. Kozuka, A. Tsukazai, M. Kawasaki
    "Magnesium doping controlled density and mobility of two-dimensional electron gas in MgxZn1-xO/ZnO heterostructures"
    Applied Physics Express 4, 091101-1-3 (2011)
    DOI: 10.1143/APEX.4.091101
  97. Y. Ishida, H. Kanto, A. Kikkawa, Y. Taguchi, Y. Ito, Y. Ota, K. Okazaki, W. Malaeb, M. Mulazzi, M. Okawa, S. Watanabe, C.-T. Chen, M. Kim, C. Bell, Y. Kozuka, H. Y. Hwang, Y. Tokura, S. Shin
    "Common origin of the circular-dichroism pattern in ARPES of SrTiO3 and CuxBi2Se3"
    Physical Review Letters 107, 077601-1-4 (2011)
    DOI: 10.1103/PhysRevLett.107.077601
    (arXiv:1108.4280)
  98. Y. Kozuka, A. Tsukazaki, D. Maryenko, J. Falson, S. Akasaka, K. Nakahara, S. Nakamura, S. Awaji, K. Ueno, M. Kawasaki
    "Insulating phase of a two-dimensional electron gas in MgxZn1-xO/ZnO heterostructures below ν = 1/3"
    Physical Review B 84, 033304-1-4 (2011)
    DOI: 10.1103/PhysRevB.84.033304
    (arXiv:1106.5605)
  99. Y. Kozuka, M. Kim, H. Ohta, Y. Hikita, C. Bell, H. Y. Hwang
    "Enhancing the electron mobility via delta-doping in SrTiO3"
    Applied Physics Letters 94, 222115-1-3 (2010)
    DOI: 10.1063/1.3524198
    (arXiv:1011.0159)
  100. Y. Kozuka, Y. Hikita, C. Bell, H. Y. Hwang
    "Dramatic mobility enhancements in doped SrTiO3 thin films by defect management"
    Applied Physics Letters 94, 012107-1-3 (2010)
    DOI: 10.1063/1.3457994
    (arXiv:1006.1564)
  101. Y. Kozuka, M. Kim, C. Bell, B. G. Kim, Y. Hikita, H. Y. Hwang
    "Two-dimensional normal-state quantum oscillations in a superconducting heterostructure"
    Nature 462, 487-490 (2009)
    DOI: 10.1038/nature08566
  102. C. Bell, S. Harashima, Y. Kozuka, M. Kim, B. G. Kim, Y. Hikita, H. Y. Hwang
    "Dominant mobility modulation by the electronic field effect at the LaAlO3/SrTiO3 interface"
    Physical Review Letters 103, 226802-1-4 (2009)
    DOI: 10.1103/PhysRevLett.103.226802
    (arXiv:0906.5310)
  103. Y. Kozuka, T. Susaki, H. Y. Hwang
    "Vanishing Hall coefficient in the extreme quantum limit in photocarrier-doped SrTiO3"
    Physical Review Letters 101, 096601-1-4 (2008)
    DOI: 10.1103/PhysRevLett.101.096601
    (arXiv:0803.0723)
  104. T. Susaki, Y. Kozuka, Y. Tateyama, H. Y. Hwang
    "Temperature-dependent polarity reversal in Au/Nb:SrTiO3 Schottky junctions"
    Physical Review B 76, 155110-1-4 (2007)
    DOI: 10.1103/PhysRevB.76.155110
    (arXiv:0708.3725)
  105. Y. Kozuka, Y. Hikita, T. Susaki, H. Y. Hwang
    "Optically tuned dimensionality crossover in photocarrier-doped SrTiO3: Onset of weak localization"
    Physical Review B 76, 085129-1-6 (2007)
    DOI: 10.1103/PhysRevB.76.085129
    (arXiv:0704.3680)
  106. Y. Hikita, Y. Kozuka, T. Susaki, H. Takagi, H. Y. Hwang
    "Characterization of the Schottky barrier in SrRuO3/Nb:SrTiO3 junctions"
    Applied Physics Letters 90, 143507-1-3 (2007)
    DOI: 10.1063/1.2719157
    (arXiv:cond-mat/0703358)
  107. Y. Kozuka, T. Susaki, H. Y. Hwang
    "Rectifying NdNiO3/Nb:SrTiO3 junctions as a probe of the surface electronic structure of NdNiO3"
    Applied Physics Letters 88, 142111-1-3 (2006)
    DOI: 10.1063/1.2193800

Reviews

  1. Joseph Falson, Yusuke Kozuka, Atsushi Tsukazaki, Masashi Kawasaki
    "Two-dimensional quantum transport in high-quality ZnO heterointerfaces"
    OYO BUTURI 84, 984-990 (2015)
    [in Japanese]
  2. Atsushi Tsukazaki, Yusuke Kozuka, Masashi Kawasaki
    "Recent development in ZnO related heterostructures towards optical and electrical applications"
    The Journal of the Institute of Electronics, Information and Communication Engineers 97, 227-232 (2014)
    [in Japanese]