Updated on 2021/10/26

写真a

 
SHIMIZU, Yasuhiro
 
Organization
Graduate School of Science Division of Material Science Solid State Physics Lecturer
Graduate School
Graduate School of Science
Undergraduate School
School of Science
Title
Lecturer

Degree 1

  1. Ph.D ( 2005.3   Kyoto University ) 

Research Interests 13

  1. quantum liquid

  2. quantum phenomena

  3. material science

  4. molecular solids

  5. condensed matter physics

  6. quantum liquids

  7. magnetic resonance

  8. Strongly correlated electron system

  9. superconductor

  10. magnetic resonance

  11. material science

  12. Strongly correlated electron system

  13. molecular solids

Research Areas 10

  1. Natural Science / Magnetism, superconductivity and strongly correlated systems  / condensed matter physics

  2. Natural Science / Semiconductors, optical properties of condensed matter and atomic physics  / magnetic resonance

  3. Nanotechnology/Materials / Applied physical properties  / superconductor/magnetism

  4. Natural Science / Semiconductors, optical properties of condensed matter and atomic physics  / magnetic resonance

  5. Nanotechnology/Materials / Functional solid state chemistry  / organic functional materials

  6. Natural Science / Magnetism, superconductivity and strongly correlated systems

  7. Nanotechnology/Materials / Functional solid state chemistry

  8. Nanotechnology/Materials / Applied physical properties

  9. Natural Science / Semiconductors, optical properties of condensed matter and atomic physics

  10. Natural Science / Semiconductors, optical properties of condensed matter and atomic physics

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Current Research Project and SDGs 12

  1. 縮重π電子系の異方的構造制御と機能化(新学術領域・公募)

  2. Development of a new ultra-high pressure magnetic resonance

  3. Precise detection of quantum liquid crystals

  4. Evolution of new quantum phases in strongly correlated multi-orbital systems

  5. 有機スピン三角格子を基盤とする複合電子機能の開発研究

  6. 光検出磁気共鳴を用いた新しい磁気測定法の開発

  7. 複合自由度が競合・協調した多軌道強相関電子系における新奇な軌道物性の探究

  8. 軌道選択モット転移と軌道液体の実験研究

  9. NMRによるフラストレートしたスピン・電荷・軌道結合系の電子状態の解明

  10. NMR study of metal-insulator transition in strongly correlated electron system

  11. 金属絶縁体転移近傍に出現する超伝導・異常金属相の電子状態の解明

  12. 遷移金属酸化物の多自由度結合系における強相関量子相の研究

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Research History 5

  1. 名古屋大学 大学院理学研究科物質理学専攻 講師

    2011.4

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    Country:Japan

  2. Nagoya University   Graduate School of Science Division of Material Science Solid State Physics   Lecturer

    2011.4

  3. Nagoya University   Graduate School of Science, Division of Material Science

    2011.4

  4. 名古屋大学高等研究院 特任講師

    2007.4 - 2011.3

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    Country:Japan

  5. SPD/RIKEN

    2005.4 - 2007.3

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    Country:Japan

Education 3

  1. Kyoto University   Graduate School, Division of Natural Science   Division of Chemistry

    2002.4 - 2005.3

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    Country: Japan

  2. Kyoto University   Graduate School, Division of Natural Science   Divisin of Chemistry

    2000.4 - 2002.3

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    Country: Japan

  3. Kyoto University   Faculty of Science

    1996.4 - 2000.3

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    Country: Japan

Professional Memberships 5

  1. Physical Society of Japan

    2013.10 - 2014.9

  2. American Physical Society

  3. 日本化学会

  4. Physical Society of Japan

  5. American Physical Society

Committee Memberships 1

  1. 日本物理学会   領域7運営委員  

    2013.3 - 2014.3   

Awards 3

  1. Excellent Teacher Award

    2021.4   Nagoya University  

  2. BCSJ Award

    2020.2   Bulletin of the Chemical Society of Japan   Canting Antiferromagnetic Spin-Order (TN = 102 K) in a Monomer Mott Insulator (ET)Ag4(CN)5 with a Diamond Spin-Lattice

    A.Otsuka, Y, Shimizu, G. Saito

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    Country:Japan

  3. 日本物理学会若手奨励賞

    2012.3   日本物理学会  

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    Country:Japan

 

Papers 58

  1. Determination of local defect density in diamond by double electron-electron resonance Reviewed International coauthorship International journal

    Shang Li, Huijie Zheng, Zaili Peng, Mizuki Kamiya, Tomoyuki Niki, Viktor Stepanov, Andrey Jarmola, Yasuhiro Shimizu, Susumu Takahashi, Arne Wickenbrock, and Dmitry Budker

    Physical Review B   Vol. 104   page: 094307/1 - 094307/10   2021.9

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Physical Society  

    Magnetic impurities in diamond influence the relaxation properties and thus limit the sensitivity of magnetic, electric, strain, and temperature sensors based on nitrogen-vacancy color centers. Diamond samples may exhibit significant spatial variations in the impurity concentrations hindering the quantitative analysis of relaxation pathways. Here, we present a local measurement technique which can be used to determine the concentration of various species of defects by utilizing double electron-electron resonance. This method will help to improve the understanding of the physics underlying spin relaxation and guide the development of diamond samples, as well as offering protocols for optimized sensing.

    DOI: 10.1103/PhysRevB.104.094307

    Other Link: https://arxiv.org/abs/2104.00744

  2. 名古屋大学におけるオンラインでの物理実験の取り組み Reviewed

    森鼻久美子、中村泰之、清水康弘、水野亮、槇瓦介

      Vol. 50   page: 32 - 35   2021.6

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

  3. Magnetic field-driven transition between valence bond solid and antiferromagnetic order in distorted triangular lattice Invited Reviewed

    Yasuhiro Shimizu, Mitsuhiko Maesato, Makoto Yoshida, Masashi Takigawa, Masayuki Itoh, Akihiro Otsuka, Hideki Yamochi, Yukihiro Yoshida, Genta Kawaguchi, David Graf, and Gunzi Saito

    Phys. Rev. Research   Vol. 3   page: 023145/1 - 023145/8   2021.5

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1103/PhysRevResearch.3.023145

    Other Link: https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.3.023145

  4. Local Observations of Orbital Diamagnetism and Excitation in Three-Dimensional Dirac Fermion Systems Bi1-xSbx Invited Reviewed International coauthorship

    Yukihiro Watanabe, Masashi Kumazaki, Hiroki Ezure, Takao Sasagawa, Robert Cava, Masayuki Itoh, Yasuhiro Shimizu

    J. Phys. Soc. Jpn.   Vol. 90   page: 053701-1 - 053701-5   2021.4

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: https://doi.org/10.7566/JPSJ.90.053701

    Other Link: https://arxiv.org/abs/2102.09917

  5. Orbital and magnetic ordering and domain-wall conduction in ferrimagnet La5Mo4O16 Reviewed

    Takuro Katsufuji, Masayuki Miyake, Makoto Naka, Masahito Mochizuki, Sota Kogo, Tomomasa Kajita, Yasuhiro Shimizu, Masayuki Itoh, Takatoshi Hasegawa, Shunsuke Shimose, Shunta Noguchi, Takuo Saiki, Takuro Sato, and Fumitaka Kagawa

    Phys. Rev. Research   Vol. 3   page: 013105-1 - 013105-17   2021.2

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: https://doi.org/10.1103/PhysRevResearch.3.013105

  6. High pressure investigation of an organic three-dimensional Dirac semimetal candidate having a diamond lattice Reviewed

    Andhika Kiswandhi, Mitsuhiko Maesato, Shinya Tomeno, Yukihiro Yoshida, Yasuhiro Shimizu, Prashant Shahi, Jun Gouchi, Yoshiya Uwatoko, Gunzi Saito, and Hiroshi Kitagawa

    Phys. Rev. B   Vol. 101   page: 245124/1-7   2020.6

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    Language:English   Publishing type:Research paper (scientific journal)  

    (ET)Ag4(CN)5 [ET = BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene] is a rare example of organic conductors that crystallizes in a diamond structure due to the tetrahedral arrangement of neighboring ET molecules. Because each ET has a +1 site charge, the band is half filled, which in combination with strong Coulomb interactions, turn (ET)Ag4(CN)5 into a Mott insulator. Recently, it was realized that this material may realize a nodal Dirac semimetal with a diamondlike lattice, whose state can be induced by suppressing the strong electron correlations. In this report, we present high pressure transport and optical studies on (ET)Ag4(CN)5. Our transport study indicates that the activation energy is highly suppressed by the application of hydrostatic pressure. At high pressures, the system varies from activated behavior into Coulomb gap variable range hopping.

    DOI: 10.1103/PhysRevB.101.245124

  7. Occupation switching of d orbitals in vanadium dioxide probed via hyperfine interactions Reviewed

    Yasuhiro Shimizu, Takaaki Jin-no, Fumitatsu Iwase, Masayuki Itoh, and Yutaka Ueda

    Phys. Rev. B   Vol. 101   page: 245123/1-9   2020.6

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    Metal-insulator transition was microscopically investigated by orbital-resolved nuclear magnetic resonance (OR-NMR) spectroscopy in a single crystal of vanadium dioxide VO2. Observations of the anisotropic
    51V Knight shift and the nuclear quadrupole frequency allow us to evaluate orbital-dependent spin susceptibility and d orbital occupations. The result is consistent with the degenerated t2g orbitals in a correlated metallic phase and the d orbital ordering in a nonmagnetic insulating phase. The predominant orbital pointing along the chain facilitates a spin-singlet formation triggering metal-insulator transition. The asymmetry of magnetic and electric hyperfine tensors suggests the d orbital reformation favored by a low-symmetry crystal field, forming a localized molecular orbital. The result highlights the cooperative electron correlation and electron-phonon coupling in Mott transition with orbital degrees of freedom.

    DOI: 10.1103/PhysRevB.101.245123

  8. Canting Antiferromagnetic Spin-Order (TN = 102 K) in a Monomer Mott Insulator (ET)Ag4(CN)5 with a Diamond Spin-Lattice Reviewed

    A. Otsuka, Y. Shimizu, G. Saito, M. Maesato, A. Kiswandhi,T. Hiramatsu, Y. Yoshida, H. Yamochi, M. Tsuchiizu, Y. Nakamura, H. Kishida, and H. Ito

    Bull. Chem. Soc. Jpn.   Vol. 93   page: 260-272   2020.2

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    The ET•+ molecules in a charge-transfer salt (ET)Ag4(CN)5 form a three-dimensional diamond spin-lattice with S = 1/2 (ET: bis(ethylenedithio)tetrathiafulvalene), where a geometrical spin-frustration is expected when an appropriate spin interaction is realized. A metallic nature has been proposed for this salt based on both band calculation and electron paramagnetic resonance measurements. We studied the crystal and band structures, optical spectra, resistivity, magnetic, and NMR measurements and found the salt to be a three-dimensional monomer Mott insulator with a resistivity of 1.8 × 102 Ω cm at room temperature (// c), though the calculated band structure showed a Dirac-like semimetallic dispersion. 1H NMR and magnetic susceptibility measurements reveal an antiferromagnetic spin ordering at TN = 102 K, above which characteristic temperature insensitive behaviors of T1−1 and spin susceptibility are observed. A weak ferromagnetism is detected below TN with a spin canting angle of ∼0.01°, possibly arising from a Dzyaloshinskii-Moriya interaction due to a lowering of the crystal symmetry. This is the first example of a weak ferromagnetic three-dimensional diamond spin-lattice among the organic charge-transfer solids

    DOI: 10.1246/bcsj.20190279

  9. Two-step gap opening across the quantum critical point in a Kitaev honeycomb magnet a-RuCl Reviewed

    Y. Nagai, T. Jinno, J. Yoshitake, J. Nasu, Y. Motome, M. Itoh, Y. Shimizu

    Phys. Rev. B   Vol. 101   page: 020414(R)/1-6   2020.1

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    A Kitaev quantum spin liquid involves fractionalized quasiparticles called itinerant Majorana fermions and localized gauge fluxes. The topological character with chiral excitations under a magnetic field is currently in an active debate. For a candidate spin liquid α−RuCl3, we report low-energy spin excitations through nuclear magnetic and quadrupole resonance measurements down to temperatures three orders of magnitude lower than the exchange energy. In a field-driven disordered state, we found the evolution of two kinds of gapped spin excitations with distinct field dependences. The result is indicative of a field-induced hybridization between fractionalized quasiparticles, as inferred by the perturbation theory for the Kitaev model. The detailed field dependence of spin dynamics across the quantum critical region shows the emergence of a gapless intermediate phase between the gapped zigzag order phase and spin-disordered phases.

    DOI: 10.1103/PhysRevB.101.020414

  10. High ambipolar mobility in a neutral radical gold dithiolene complex Reviewed

    A. Mizuno, H. Benjamin, Y. Shimizu, Y. Shuku, M. M. Matsushita, N. Robertson, K. Awaga,

    Adv. Func. Mater   Vol. 29   page: 1904181/1-10   2019.8

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    DOI: 10.1002/adfm.201904181

  11. Molecular diamond lattice antiferromagnet as a Dirac semimetal candidate Reviewed

    Yasuhiro Shimizu, Akihiro Otsuka, Mitsuhiko Maesato, Masahisa Tsuchiizu, Akiko Nakao, Hideki Yamochi, Takaaki Hiramatsu, Yukihiro Yoshida, and Gunzi Saito

    Phys. Rev. B   Vol. 99   page: 174417   2019.5

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    The ground state of a molecular diamond-lattice compound (ET)Ag4(CN)5 is investigated by the magnetization and nuclear magnetic resonance spectroscopy. We found that the material exhibits the Mott insulating ground state with antiferromagnetic long-range ordering at 102 K. The ordered moment shows weak-ferromagnetism with a tiny canting angle. The spin susceptibility is well fitted into the diamond-lattice Heisenberg model with a nearest neighbor exchange coupling of 230 K, indicating the less frustrated interactions. The transition temperature elevates up to 195 K by applying pressure of 2 GPa, which records the highest temperature among organic molecular magnets. The first-principles band calculation without electron correlations suggests that the system is accessible to a three-dimensional topological semimetal with nodal Dirac lines, which has been anticipated on a half-filling diamond lattice.

    DOI: 10.1103/PhysRevB.99.174417

  12. Fullerene and endometallofullerene Kagome lattices with symmetry-forced spin frustration

    Konarev Dmitri V., Khasanov Salavat S., Shimizu Yasuhiro, Kuzmin Alexey V., Otsuka Akihiro, Yamochi Hideki, Saito Gunzi, Lyubovskaya Rimma N.

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   Vol. 21 ( 4 ) page: 1645-1649   2019.1

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    DOI: 10.1039/c8cp07017b

    Web of Science

  13. Transport anisotropy and electron correlations in the layered molecular compounds Z[Pd(dmit)(2)](2) (Z = Me4N, Et2Me2As, EtMe3P) with different interlayer coupling Reviewed

    Shimizu Yasuhiro, Kato Reizo

    PHYSICAL REVIEW B   Vol. 97   page: 125107   2018.3

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    In-plane resistivity and out of plane resistivity were investigated across the pressure induced Mott transition in molecular Mott insulators Z[Pd(dmit)2]2 (Z = Et2Me2As, Me4N, and EtMe3P) having a triangular
    lattice. All three compounds exhibit superconducting transition with Tc = 5.5-7.0 K in the metallic phase near the Mott insulating phase. For the Et2Me2As salt, the anisotropy exceeds 10^3 at low temperatures,
    indicating a highly two-dimensional electronic state with incoherent interlayer hopping. The Me4N salt has a
    smaller anisotropy exhibiting a weak interlayer coupling. The resistivity is dominated by electron-electron scattering in the metallic state for these two compounds, as expected in a correlated Fermi liquid. On the other hand, the EtMe3P salt with a valence bond order state becomes a nearly three-dimensional metal across the Mott transition, in which the electron correlation is strongly suppressed. Instead, the electron-phonon scattering plays a significant
    role in the resistivity. The different interlayer coherence is quantitatively explained by the calculated interlayer transfer integrals between Pd(dmit)2 molecules. These results suggest that the dimensionality governs the nature of electron correlations in the Fermi liquid state.

    DOI: 10.1103/PhysRevB.97.125107

    Web of Science

  14. Symmetry Preservation and Critical Fluctuations in a Pseudospin Crossover Perovskite LaCoO3 Reviewed

    Shimizu Yasuhiro, Takahashi Takuya, Yamada Syunpei, Shimokata Ayako, Jin-no Takaaki, Itoh Masayuki

    PHYSICAL REVIEW LETTERS   Vol. 119   page: 267203   2017.12

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    Spin-state crossover beyond a conventional ligand-field theory has been a fundamental issue in condensed matter physics. Here, we report microscopic observations of spin states and low-energy dynamics through orbital-resolved NMR spectroscopy in the prototype compound LaCoO3. The 59Co NMR spectrum shows the preserved crystal symmetry across the crossover, inconsistent with d orbital ordering due to the Jahn-Teller distortion. The orbital degeneracy results in a pseudospin excited state with an orbital moment observed as 59Co hyperfine coupling tensors. We found that the population of the excited state evolves above the heart crossover temperature. The crossover involves critical spin-state fluctuations emerging under the magnetic field. These results suggest that the spin-state crossover can be mapped into a statistical problem, analogous to the supercritical liquid in liquid-gas transition.

    DOI: 10.1103/PhysRevLett.119.267203

    Web of Science

  15. Trimerization and orbital ordering in Ba1-xSrxV13O18 Reviewed

    T. Kajita, Y. Obata, Y. Kakesu, Y. Imai, Y. Shmizu, M. Itoh, H. Kuwahara, T. Katsufuji

    Physical Review B   Vol. 96   page: 245126   2017.12

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    We studied the physical properties of Ba1-xSrxV13O18 single crystals, which exhibit three different phases
    caused by the orbital and charge degrees of freedom in V t2g states. We found from the magnetic susceptibility
    and the NMR measurement that the low-temperature phase of this series of compounds is characterized by the spin-singlet state. We also found from the electrical resistivity and optical conductivity spectra that these
    compounds become heavily anisotropic in the low-temperature phase with V trimerization, indicating that the orbital ordering of V t2g states causes the anisotropy of the electronic structure of this series of compounds.

    DOI: 10.1103/PhysRevB.96.245126

  16. Design and Preparation of a Quantum Spin Liquid Candidate kappa-(ET)(2)Ag-2(CN)(3) Having a Nearby Superconductivity

    Hiramatsu Takaaki, Yoshida Yukihiro, Saito Gunzi, Otsuka Akihiro, Yamochi Hideki, Maesato Mitsuhiko, Shimizu Yasuhiro, Ito Hiroshi, Nakamura Yuto, Kishida Hideo, Watanabe Masashi, Kumai Reiji

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   Vol. 90 ( 9 ) page: 1073-1082   2017.9

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    DOI: 10.1246/bcsj.20170167

    Web of Science

  17. 3D spin-liquid state in an organic hyperkagome lattice of Mott dimers Reviewed

    A. Mizuno, Y. Shuku, M. M. Matsushita, M. Tsuchiizu, Y. Hara, N. Wada, Y. Shimizu, K. Awaga

    Physical Review Letters   Vol. 119   page: 057201   2017.7

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    DOI: 10.1103/PhysRevLett.119.057201

  18. Pressure-Tuned Exchange Coupling of a Quantum Spin Liquid in the Molecular Triangular Lattice κ-(ET)2Ag2(CN)3 Reviewed

    Y. Shimizu, T. Hiramatsu, M. Maesato, A. Otsuka, H. Yamochi, A. Ono, M. Itoh, M. Yoshida, M. Takigawa, Y. Yoshida, G. Saito

    Physical Review Letters   Vol. 117   page: 107203   2016.8

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    The effects of pressure on a quantum spin liquid are investigated in an organic Mott insulator ET2Ag2CN3 with a spin triangular lattice.

    DOI: 10.1103/PhysRevLett.117.107203

  19. Pressure-induced superconductivity in the antiferromagnet κ-(ET)2CF3SO3 with quasi-one-dimensional triangular spin lattice Reviewed

    H. Ito, T. Asai, Y. Shimizu, H. Hayama, Y. Yoshida, G. Saito

    Physical Review B   Vol. 94   page: 020503(R)   2016.7

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    DOI: 10.1103/PhysRevB.94.020503

  20. Local electronic state in the half-metallic ferromagnet CrO2 investigated by site-selective 53Cr NMR measurements Reviewed

    H. Takeda, Y. Shimizu, Y. Kobayashi, M. Itoh, T. Jin-no, M. Isobe, Y. Ueda, S. Yoshida, Y. Muraoka, T. Yokoya

    Physical Review B   Vol. 93   page: 235129   2016.6

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    DOI: 10.1103/PhysRevB.93.235129

  21. Spin Frustration in Antiperovskite Systems (TTF+ or TSF+)3[(Mo6X14)2Y] Reviewed

    Takaaki Hiramatsu, Yukihiro Yoshida, Gunzi Saito, Akihiro Otsuka, Hideki Yamochi, Yasuhiro Shimizu, Yuma Hattori, Yuto Nakamura, Hideo Kishida, Hiroshi Ito, Kaplan Kirakci, Stephane Cordier, Christiane Perrin

    Journal of Materials Chemistry C     2015.10

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    DOI: 10.1039/C5TC02075A

  22. Magnetic fluctuations and possible formation of a spin-singlet cluster under pressure in the heavy-fermion spinel LiV2O4 probed by 7Li and 51V NMR Reviewed

    H.Takeda, Y. Kato, M. Yoshimura, Y. Shimizu, M. Itoh, S. Niitaka, H. Takagi

    Physical Review B   Vol. 92   page: 045103/1-8   2015.7

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    DOI: DOI: 10.1103/PhysRevB.92.045103

  23. Spin-disordered quantum phases in a quasi-one-dimensional triangular lattice Reviewed

    Y. Yoshida, H. Ito, M. Maesato, Y. Shimizu, H. Hayama, T. Hiramatsu, Y. Nakamura, H. Kishida, T. Koretsune, C. Hotta, G. Saito

    Nature Physics   Vol. 11   page: 679-683   2015.6

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    DOI: 10.1038/NPHYS3359

  24. Site-selective Mott transition in a quasi-one-dimensional vanadate V6O13 Reviewed

    Y. Shimizu, S. Aoyama, T. Jinno, M. Itoh, Y. Ueda

    Physical Review Letters   Vol. 114   page: 166403/1-5   2015.4

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    DOI: 10.1103/PhysRevLett.114.166403

  25. Zero-field nuclear magnetic resonance spectroscopy of viscous liquids Reviewed

    Y. Shimizu, J.W. Blanchard, S. Pustelny, G. Saielli, A. Bagno, M.P. Ledbetter, D. Budker, A. Pines

    Journal of Magnetic Resonance   Vol. 250   page: 1-6   2014.11

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    DOI: doi:10.1016/j.jmr.2014.10.012

  26. Spin disorder in an Ising honeycomb chain cobaltate Reviewed

    H. Igarashi, Y. Shimizu, Y. Kobayashi, M. Itoh

    Phys. Rev. B   Vol. 89   page: 054431   2014.2

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  27. Ultrasonic investigation of the transition at 6 K in the spin-liquid candidate κ-(BEDT-TTF)2Cu2(CN)3 Reviewed

    M. Poirier, M. Lafontaine, K. Miyagawa, K. Kanoda, Y. Shimizu

      Vol. 89   page: 045138   2014.1

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    DOI: http://dx.doi.org/10.1103/PhysRevB.89.045138

  28. Orbital reformation with vanadium trimerization in d2 triangular lattice LiVO2 revealed by 51V NMR Reviewed

    T. Jin-no, Y. Shimizu, M. Itoh, S. Niitaka, H. Takagi

    Phys. Rev. B   Vol. 87   page: 075135   2013.2

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    DOI: 10.1103/PhysRevB.87.075135

  29. An orbital selective spin liquid in frustrated spinel LiV2O4 Reviewed

    Y. Shimizu, H. Takeda, M. Itoh, S. Niitaka, H. Takagi

    Nature Communications   Vol. 3   page: 981   2012.8

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    巨大な有効質量をもつ典型物質であるスピネル酸化物LiV2O4において、その微視的起源を軌道分解NMRにより調べた。局在的なd軌道上のスピンが極低温まで磁気秩序を起さない量子液体状態にあることを見出した。

    DOI: 10.1038/ncomms1979

  30. Uncovering the magnetic and non-magnetic phases of a quantum spin liquid Reviewed

    F.L. Pratt, P.J. Baker, S.J. Blundell, T. Lancaster, S. Ohira-Kawamura, C. Baines, Y. Shimizu, K. Kanoda and I. Watanabe

    Nature   Vol. 471   page: 612   2011.4

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  31. Metal-insulator transition in the hollandite K2V8O16 with a frustrated zigzag ladder probed by 51V NMR Reviewed

    Y. Shimizu, K. Okai, M. Itoh, M. Isobe, J. Yamaura, T. Yamauchi, Y. Ueda

    Physical Review B   Vol. 83   page: 155111   2011.4

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  32. Anisotropic spin dynamics in the frustrated chain Ca3Co2O6 detected by single-crystal 59Co NMR Reviewed

    Y. Shimizu, M. Horibe, H. Nanba, T. Takami, and M. Itoh

      Vol. 82   page: 094430   2010.9

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  33. Pressure-induced superconductivity and Mott transition in spin-liquid κ-(ET)2Cu2(CN)3 probed by 13C NMR Reviewed

    Y. Shimizu, H. Kasahara, A. Furuta, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

      Vol. 81   page: 224508   2010.6

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    Language:English   Publishing type:Research paper (scientific journal)  

  34. Formation of a three-dimensional network of V trimers in A2V13O22 (A =Ba, Sr), Reviewed

    J. Miyazaki, K. Matsudaira, Y. Shimizu, M. Itoh, Y. Nagamine, S. Mori, J. E. Kim, K. Kato, M. Takata, and T. Katsufuji

    Phys. Rev. Lett.   Vol. 104   page: 207201   2010.5

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  35. Pressure induced antiferromagnetic fluctuations in the pnictide superconductor FeSe0.5Te0.5: 125Te NMR study Reviewed

    Y. Shimizu, T. Yamada, T. Takami, S. Niitaka, H. Takagi, and M. Itoh

    J. Phys. Soc. Jpn.   Vol. 78   page: 123707   2009.12

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  36. High-pressure 51V NMR study of the magnetic phase diagram and metal-insulator transition in the quasi-one-dimensional β-Na0.33V2O5 Reviewed

    Taisuke Suzuki, Ichihiro Yamauchi, Yasuhiro Shimizu, Masayuki Itoh, Nao Takeshita,Chieko Terakura, Hidenori Takagi, Yoshinori Tokura, Touru Yamauchi, and Yutaka Ueda

    Phys. Rev. B   Vol. 79   page: 081101(R)   2009.2

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  37. Spin-singlet formation in the geometrically frustrated spinel oxide AlV2O4: 51V and 27Al NMR measurements Reviewed

    Y. Shimizu*, M. Takana, M. Itoh, T. Katsufuji

    Physical Review B   Vol. 78   page: 14423-1 – 14423-6   2008

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  38. Thermodynamic properties of a spin-1/2 spin-liquid in a -type organic salt Reviewed

    S. Yamashita, Y. Nakazawa, M. Oguni, Y. Oshima, H. Nojiri, Y. Shimizu, K. Miyagawa, K. Kanoda

    Nature Physics   Vol. 4   page: 459 - 462   2008

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  39. Reentrant Mott transition from a Fermi liquid to a spin-gapped insulator in an organic spin-1/2 triangular-lattice antiferromagnet Reviewed

    Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato

    J. Phys.: Condens. Matter   Vol. 19 ( 14 ) page: 145240   2007.4

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    The pressure-induced Mott transition is investigated in a quasi-two-dimensional molecular conductor, EtMe3P[Pd(dmit)2]2 (P 21/m) with a triangular lattice, which shows a valence bond solid state at ambient pressure. Near the critical pressure of the Mott boundary, an insulator-to-metal transition occurs at 18 K, followed by a first-order reentrant metal-to-insulator transition below 12 K. Finally, a superconducting transition from the insulating state is observed at 5.2 K. The reentrant metal–insulator transition temperature is lowered by application of magnetic field. The result indicates the presence of a spin gap diminished by the Zeeman energy in the reentrant insulating phase neighbouring on the superconducting phase.

  40. Mott transition in a valence-bond solid insulator with triangular lattice Reviewed

    Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, R. Kato

    Physical Review Letters   Vol. 99   page: 256403-1 - 256403-4   2007

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  41. Emergence of inhomogeneous moments from spin liquid in the triangular-lattice Mott insulator κ-(ET)2Cu2(CN)3 Reviewed

    Y. Shimizu, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

    Physical Review B   Vol. 73   page: R140407   2006.4

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    The static and dynamic local spin susceptibility of the organic Mott insulator -(ET)2Cu2(CN)3, a model material of the spin-1/2 triangular lattice, is studied by 13C NMR spectroscopy from room temperature down to 20 mK. We observe an anomalous field-dependent spectral broadening with the continuous and bipolar shift distribution, appearing without the critical spin fluctuations. It is attributable to spatially nonuniform magnetizations induced in the spin liquid under magnetic fields. The amplitude of the magnetization levels off below 1 K, while the low-lying spin fluctuations survive toward the ground state, as indicated by the temperature profile of the relaxation rates.

  42. Spin Liquid State in κ-(BEDT-TTF)2Cu2(CN)3 Studied by Muon Spin Relaxation Method Reviewed

    S. Ohira, Y. Shimizu, K. Kanoda, G. Saito

    Journal of Low Temperature Physics   Vol. 142   page: 153   2006

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  43. Superconductivity emerging from spin-liquid Mott insulator in triangular lattice system Reviewed

    Y. Shimizu, H. Kasahara, K. Kurosaki, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

    AIP Conference Proceedings   Vol. 850   page: 1087   2006

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  44. Inhomogeneous spin state in a spin liquid on a triangular lattice under a magnetic field Reviewed

    Y. Shimizu, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

    AIP Conference Proceedings   Vol. 850   page: 611   2006

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  45. Depressed charge gap in the triangular-lattice Mott insulator κ-(ET)2Cu2(CN) Reviewed

    I. Kezsmarki, Y. Shimizu, G. Mihaly, Y. Tokura, K. Kanoda, and G. Saito

    Physical Review B   Vol. 74   page: R201101   2006

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  46. High-pressure study of a doped-type organic superconductor, κ-(BEDT-TTF)4Hg2.89Br8 Reviewed

    T. Okuhata, T. Nagai, H. Taniguchi, K. Satoh, T. Itou, Y. Shimizu, K. Miyagawa, Y. Ishii, N. Tajima, and R. Kato

    J. Low Temperature Physics   Vol. 142   page: 547   2006

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  47. Mott Transition from a Spin Liquid to a Fermi Liquid in the Spin-Frustrated Organic Conductor κ-(ET)2Cu2(CN)3 Reviewed

    K. Kurosaki, Y. Shimizu, K. Miyagawa, K. Kanoda, and G. Saito,

    Physical Review Letters   Vol. 95   page: 177001   2005

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    The pressure-temperature phase diagram of the organic Mott insulator -(ET)2Cu2(CN)3, a model system of the spin liquid on triangular lattice, has been investigated by 1H NMR and resistivity measurements. The spin-liquid phase is persistent before the Mott transition to the metal or superconducting phase under pressure. At the Mott transition, the spin fluctuations are rapidly suppressed and the Fermi-liquid features are observed in the temperature dependence of the spin-lattice relaxation rate and resistivity. The characteristic curvature of the Mott boundary in the phase diagram highlights a crucial effect of the spin frustration on the Mott transition.

  48. NMR study of spin liquid state and Mott transition in the spin-frustrated organic system, κ-(ET)2Cu2(CN)3 Reviewed

    Y. Shimizu, Y. Kurosaki, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

    Synthetic Metals   Vol. 152   page: 393   2005

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  49. Spin liquid in a spin-frustrated organic Mott insulator Invited Reviewed

    . Shimizu, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

    Progress of Theoretical Physics Supplement   Vol. 159   page: 52   2005

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  50. Spin-liquid behavior and superconductivity in κ-(BEDT-TTF)2X: The role of uniaxial strain Reviewed

    M. Maesato, Y. Shimizu, T. Ishikawa, G. Saito, K. Miyagawa, and K. Kanoda

    Journal de Physique IV (France)   Vol. 114   page: 227   2004

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  51. Infrared and Raman Study of the Charge-ordered State of θ-(ET)2Cu2CN[N(CN)2]2 Reviewed

    Yamamoto, K. Yakushi, Y. Shimizu and G. Saito

    Journal of the Physical Society of Japan   Vol. 73   page: 2326   2004

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  52. 1H NMR study of the organic Mott insulator with triangular lattice, κ-(ET)2Cu2(CN)3 Reviewed

    Y. Shimizu, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

    Journal de Physique IV (France)   Vol. 114   page: 377   2004

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  53. Spin liquid state in an organic Mott insulator with a triangular lattice Reviewed

    Y. Shimizu, K. Miyagawa, K. Kanoda, M. Maesato, and G. Saito

    Physical Review Letters   Vol. 91   page: 107001   2003

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    1H NMR and static susceptibility measurements have been performed in an organic Mott insulator with a nearly isotropic triangular lattice, κ-(BEDT-TTF)2Cu2(CN)3, which is a model system of frustrated quantum spins. The static susceptibility is described by the spin S=1/2 antiferromagnetic triangular-lattice Heisenberg model with the exchange constant J∼250  K. Regardless of the large magnetic interactions, the 1H NMR spectra show no indication of long-range magnetic ordering down to 32 mK, which is 4 orders of magnitude smaller than J. These results suggest that a quantum spin liquid state is realized in the close proximity of the superconducting state appearing under pressure.

  54. Anisotropy in the superconducting transition temperature of k-(ET)2X Reviewed

    M. Maesato, Y. Shimizu, T. Ishikawa, and G. Saito

    Synthetic Metals   Vol. 137   page: 1243   2003

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  55. Transport properties of a Mott insulator κ-(ET)2Cu2(CN)3 under the uniaxial strain Reviewed

    Y. Shimizu, M. Maesato, G. Saito, O.O.Drozdova, and L. Ouahab

    Synthetic Metals   Vol. 133   page: 225   2003

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  56. Magnetic properties of a Mott insulator κ-(ET)2Cu2(CN)3 Reviewed

    Y. Shimizu, M. Maesato, G. Saito, K. Miyagawa, and K. Kanoda

    Synthetic Metals   Vol. 137   page: 1247   2003

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  57. Superconductivity of a θ-type ET salt prepared using CuCN and Ph4PN(CN)2 as electrolyte Reviewed

    Y.Shimizu, M. Maesato, K. Ookubo, O. O.Drozdova, and G. Saito

    Molecular Crystals Liquid Crystals   Vol. 380   page: 135   2002

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  58. The crystal and electronic structure analysis of (OMTTF)2[Ni(tdas)2], where OMTTF = octamethylenetetrathiafulvalene and tdas = 1,2,5-thiadiazole-3,4-dithiolate Reviewed

    H. Yamochi, N. Sogoshi, Y. Shimizu, K. Matsumoto, and G. Saito

    Journal of Material Chemistry   Vol. 11   page: 2216   2001

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Books 2

  1. Atomic Physics

    Yasuhiro Shimizu(translation), D. Budker, D.F.Kimball, D.P. DeMille( Role: Sole translator)

    Kyoritsu Publisher  2019.3  ( ISBN:978-4-320-03608-6

  2. 三角格子有機モット絶縁体におけるスピン液体

    清水康弘, 宮川和也, 鹿野田一司, 前里光彦, 齋藤軍治( Role: Joint author)

    固体物理  2004 

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    Language:Japanese

KAKENHI (Grants-in-Aid for Scientific Research) 14

  1. 量子液晶の精密計測

    2019.4 - 2025.3

    科学研究費補助金  新学術領域研究

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    Authorship:Coinvestigator(s) 

  2. π造形科学: 縮重π電子系の異方的構造制御と機能

    2017.4 - 2019.3

    科学研究費補助金  新学術領域研究

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    Authorship:Principal investigator 

  3. 新しい超高圧磁気測定法の開発

    2016.4 - 2018.3

    科学研究費補助金  研究成果公開促進費 (研究成果公開発表)

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    Authorship:Principal investigator 

  4. 有機スピン三角格子を基盤とする複合電子機能の開発研究

    2011.4 - 2016.3

    科学研究費補助金  基盤研究(S)

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    Authorship:Coinvestigator(s) 

  5. Development of a new magnetometry using optically detected magnetic resonances

    2013.4 - 2015.3

    Grant-in-Aid for Scientific Research 

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    Authorship:Principal investigator 

  6. 複合自由度が競合・協調した多軌道強相関電子系における新奇な軌道物性の探究

    2012.4 - 2015.3

    科学研究費補助金  基盤研究(B)

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    Authorship:Coinvestigator(s) 

  7. 軌道選択モット転移と軌道液体の実験研究

    2010.4 - 2013.3

    科学研究費補助金  若手研究(A)

    清水 康弘

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    Authorship:Principal investigator 

  8. NMRによるフラストレートしたスピン・電荷・軌道結合系の電子状態の解明

    2010.4 - 2012.3

    科学研究費補助金  特定領域研究

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    Authorship:Coinvestigator(s) 

  9. 金属絶縁体転移近傍に出現する超伝導・異常金属相の電子状態の解明

    2007.4 - 2009.3

    科学研究費補助金  若手研究(B)

    清水 康弘

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  10. 遷移金属酸化物の多自由度結合系における強相関量子相の研究

    2007.4 - 2009.3

    科学研究費補助金  基盤研究(B)

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    Authorship:Coinvestigator(s) 

  11. 縮重π電子系の異方的構造制御と機能化

    Grant number:17H05151  2017.4 - 2019.3

    新学術領域研究(研究領域提案型)

    清水 康弘

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    Grant amount:\6500000 ( Direct Cost: \5000000 、 Indirect Cost:\1500000 )

    ダイアモンド格子を有するモット絶縁体(ET)Ag4(CN)5の基底状態を核磁気共鳴実験等を用いて調べた結果、高温(102 K)での反強磁性磁気秩序を見いだした(Physical Review B, 2019, in press)。さらに、圧力下(2GPa)では、195 Kまで転移温度が上昇することを発見した。これは、π電子系として世界最高記録を更新する成果である。
    新規フラストレート磁性体に特有の物性を開拓するために、Russian Academy of Scienceとの共同研究により、カゴメ格子をもつフラーレン錯体(Bu3MeP)C60を新たに合成し、磁気的な基底状態調べた。その結果、低温まで磁気秩序が起きない量子スピン液体の可能性があることを突き止めた(Phys. Chem. Chem. Phys., 2019, 21, 1645)。フラーレン錯体の量子スピン液体としては、初めての例である。
    異方的な電子状態と輸送特性の相関を解明するために、様々な層間相互作用をもつ超伝導体Z[Pd(dmit)2]2 (Z = Me4N,Et2Me2As,EtMe3P)の電気抵抗率の圧力変化を調べた結果、等方的な系と異方的な系とで電子-電子散乱の性質が大きく異なることを見出した(Physical Review B, 2018, 97, 125107)。
    幾何学的なフラストレーションを有するカイラルなラジカル塩(TBA)1.5(NDI-Δ)の基底状態について極低温までの物性測定を行った結果、量子スピン液体で期待される特異な振る舞いを観測した(Physical Review Letters, 2017, 119, 057201)。三次元的なπ電子系では最初の例である。
    平成30年度が最終年度であるため、記入しない。
    平成30年度が最終年度であるため、記入しない。

  12. 多軌道電子系を持つ量子物質で発現する新奇物性の探究

    Grant number:19H01837  2019.4 - 2023.3

    科学研究費補助金  基盤研究(B)

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    Authorship:Coinvestigator(s) 

  13. π造形科学: 縮重π電子系の異方的構造制御と機能

    2017.4 - 2019.3

    文部科学省  科学研究費助成事業  新学術領域研究

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    Grant type:Competitive

  14. Investigation on novel quantum phases appeared between itinerant and localized regions in multi-orbital electron systems

    Grant number:16H04012  2016.4 - 2019.3

    Itoh Masayuki

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    Strongly correlated multi-orbital d electron systems between itinerant and localized regions show novel quantum phenomena due to the multi-orbital effect. In this study we have performed characteristic nuclear magnetic resonace (NMR) experiments such as orbital-resolved NMR to understand the phenomena of the strongly correlated electron systems. We obtained interesting results of electronic phase diagram of a superconducting system, charge order in a one-dimensional conductor, nematic order and fluctuation in iron-based superconductors, electronic states of a spin-crossover material, hidden order in a degenerated electron system, magnetic excitations in a candidate of the Kitaev spin liquid, and high-pressure properties of an excitonic-insulator candidate.

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Teaching Experience (On-campus) 23

  1. Condensed Matter Physcs III

    2019

  2. 物理学実験

    2017

  3. 物理学実験(理学部)

    2019

  4. 基礎セミナーA

    2017

  5. 物理学実験

    2016

  6. 基礎セミナーA

    2016

  7. 物理学実験(農学部・情報学部)

    2019

  8. 物理学実験(農学部・情報学部)

    2018

  9. 物理学実験(理学部)

    2018

  10. 物理学実験(B3)

    2015

  11. 基礎セミナーA

    2015

  12. 基礎セミナーA

    2014

  13. 物理学実験(B3)

    2014

  14. 物理学実験(B3)

    2013

  15. 基礎セミナーA

    2013

  16. 物理学実験(B3)

    2012

  17. 基礎セミナーA

    2012

  18. 総合演習

    2011

  19. 物理学実験(B3)

    2011

  20. 物理学実験(B3)

    2010

  21. 物理学実験(B3)

    2009

  22. 物理学実験(B3)

    2008

  23. 物理学実験(B3)

    2007

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