Masafumi Tamura, Dr. Sci.
博士(理学)  田 村  雅 史

Senior Scientist / Condensed Molecular Materials Lab. / RIKEN

Was Born in Kyoto in 1964,

Received BS in 1986 from The University of Tokyo (Inorganic Synthesis Lab., Department of Chemistry, Faculty of Science),
昭和61年 東京大学理学部化学科(無機合成化学研究室)卒

and M. Sci. Degree in 1988 from The University of Tokyo (Physical Chemistry II Lab., Department of Chemistry, Faculty of Science),
昭和61年〜平成2年 東京大学大学院理学系研究科化学専攻物理化学第二教室(黒田晴雄教授)にて

"Polarized Infrared Reflectivity Spectra of Conducting Molecular Crystals" PDF file (2.5 MB)
分子性導体の偏光赤外反射分光の研究 PDF file (2.5 MB)
Moved to The Institute of Solid State Physics, The University of Tokyo (Research Associate in Kinoshita Lab., Condensed Matter Division) in 1990,
平成2〜7年 東京大学物性研究所助手(木下實教授の研究室)
"Magnetism of Organic Magnets and Molecular Magnetic Materials"
Received Dr. Sci. Degree (for "Optical Study of the Electronic Structures of Molecular Conductors") in 1995 from The University of Tokyo, PDF file (1.8 MB)
平成7年 博士(理学)学位取得 「分子性伝導体の電子構造の光学的研究」(東京大学)PDF file (1.8 MB)

Moved to Toho University (Lecturer in Solid State Physics Lab., Department of Physics, Faculty of Science) in 1995,
平成7〜12年 東邦大学理学部物理学科物性物理学教室講師(梶田晃示教授,西尾豊教授)
"Transport Properties of Molecular Conductors",
"Development of Rare-Earth Containing Molecular Conductors"
and Has been working at Condensed Molecular Materials Lab. in RIKEN since 2000.

Selected Papers of My Favorite Work,

  1. M. Tamura, A. Nakao, and R. Kato
    "Frustration-Induced Valence-Bond Ordering in a New Quantum Triangular Antiferromagnet Based on [Pd(dmit)2] "
    J. Phys. Soc. Jpn., 75(9), 093701/1-093701/4 (2006).  Papers of Editors' Choice
    Discovery of a Spin-Gapped Phase with Spontaneous Breaking of Lattice Translational Symmetry for the First Time in a frustrated 2D Quantum Spin System
  2. M. Tamura, K. Takenaka, H. Takagi, S. Sugai, A. Tajima, and R. Kato
    "Spectroscopic evidence for the low-temperature charge-separated state of [Pd(dmit)2] salts"
    Chem. Phys. Lett., 411, 133-137 (2005).
    Expeimental Study of the New "Complete Charge Separation"
  3. M. Tamura and R. Kato
    "Valence instability in a dimer of two-orbital system: possible charge separation due to 'negative U' effect"
    Chem. Phys. Lett., 387, 448-452 (2004).
    Theoretical Analysis of the New "Complete Charge Separation" ---HOMO-LUMO Interplay in a Dimeric Unit
  4. M. Tamura and R. Kato
    "Effective on-site repulsion in molecular conductors with dimeric structure: Is the transfer integral a good measure of correlation?"
    J. Phys. Soc. Jpn., 73, 3108-3110 (2004).
    The Effective Electron Correlation in a Dimer is due to the Coulomb Repulsion, rather than to the Intermolecular Transfer Interaction
  5. "Magnetic susceptibility of beta'-[Pd(dmit)2] salts (dmit = 1, 3-dithiol-2-thione-4, 5-dithiolate, C3S5): evidence for frustration in spin-1/2 Heisenberg antiferromagnets on a triangular lattice"
    M. Tamura and R. Kato: J. Phys.: Condensed Matter 14 (2002) L729
    The first experimental evidence for magnetic frustration in a molecular conductor with quasi-triangular lattice
  6. "Novel BEDT-TTF salts containing rare earth ions, (ET)4Ln(NCS)6 CH2Cl2"
    M. Tamura, F. Matsuzaki, Y. Nishio, K. Kajita, T. Kitazawa, H. Mori and S. Tanaka: Synth. Met. 102 (1999) 1716,
    "pi-f Composite Metals"
    M. Tamura, K. Yamanaka, Y. Mori, Y. Nishio, K. Kajita, H. Mori, S. Tanaka, J.-I. Yamaura, T. Imakubo, R. Kato, Y. Misaki, K. Tanaka: Synth. Met. 120(2001) 1043
    The first reports of the molecular conductors based on rare-earth complex anions and pi-donors
  7. "Isolation of Crystals of a Planar Nitronyl Nitroxide Radical: 2-Phenylbenzimidazol-1-yl-N,N'-dioxide (PBIDO)"
    Y. Kusaba, M. Tamura, Y. Hosokoshi, M. Kinoshita H. Sawa, R. Kato and H. Kobayashi: J. Mater. Chem. 7 (1997) 1377
    Synthesis, crystal structure and magnetism of the first example of a stable crystal of a purely sp2 organic radical.
  8. "Enhanced Magnetic Susceptibility of (DI-DCNQI)2Cu"
    M. Tamura, Y. Kashimura, H. Sawa, S. Aonuma, R. Kato and M. Kinoshita: Solid State Commun. 93 (1995) 585.
    Discovery of the first example of itinerant electron magnetism in molecular conductors.
  9. "Analysis of de Haas-van Alphen Oscillations and Band Structure of an Organic Superconductor, theta-(BEDT-TTF)2I3"
    M. Tamura, H. Kuroda, S. Uji, H. Aoki, M. Tokumoto, A. G. Swanson, J. S. Brooks, C. C. Agosta and S. T. Hannahs: J. Phys. Soc. Jpn. 63 (1994) 615.
    The shape of the Fermi surface predicted by the previous optical study was confirmed by the quantum oscillation. Reliability of the transfer integrals based on the Huckel calculations was also examined.
    以前に分光実験から予測していたθ-(BEDT-TTF)2I3のフェルミ面が,de Haas-van Alphen振動という現象の観測によって確認された話.ついでに,いわゆる拡張ヒュッケル計算に基づくバンド計算の信頼性にも言及.
  10. "Magnetic Study of Metal-Insulator-Metal Transitions in (DMe-DCNQI-alpha,alpha'-d2)2Cu"
    M. Tamura, H. Sawa, S. Aonuma, R. Kato and M. Kinoshita: J. Phys. Soc. Jpn. 63 (1993) 429.
    Conclusive results for the M-I-M reentrant transition
  11. "Weak Ferromagnetism and Magnetic Anisotropy in Cu Salt of Fully Deuterated DMe-DCNQI, (DMe-DCNQI-d8)2Cu"
    M. Tamura, H. Sawa, S. Aonuma, R. Kato, M. Kinoshita and H. Kobayashi: J. Phys. Soc. Jpn. 62 (1993) 1470.
    "Weak Ferromagnetism in (DBr-DCNQI)2Cu (DBr-DCNQI = 2,5-dibromo-N,N'-dicyanoquinonediimine)"
    M. Tamura, H. Sawa, Y. Kashimura, S. Aonuma, R. Kato and M. Kinoshita: J. Phys. Soc. Jpn. 63 (1993) 425.
    Dicovery of Small Spontaneous Magnetization in (DCNQI)2Cu.
  12. "Low-temperature Magnetic Properties of the Ferromagnetic Organic Radical, p-Nitrophenyl Nitronyl Nitroxide"
    Y. Nakazawa, M. Tamura, N. Shirakawa, D. Shiomi, M. Takahashi, M. Kinoshita and M. Ishikawa: Phys. Rev. B 46 (1992) 8906.
    The comprehensive study of the first purely organic ferromagnet, beta-p-NPNN and its polymorphs, the gamma- and delta-phases.
  13. "Reflectance Spectra of Some Two-dimensional Organic Metals Based on BEDT-TTF and [Ni(dmit)2]"
    M. Tamura, R. Masuda, T. Naito, H. Tajima, H. Kuroda, A. Kobayashi, K. Yakushi, R. Kato, H. Kobayashi, M. Tokumoto, N. Kinoshita and H. Anzai : Synth. Met. 42 (1991) 2499.
    A brief summary of my optical study.
  14. "Reflectance Spectra of kappa-(BEDT-TTF)2I3: Electronic Structure of Dimeric BEDT-TTF Salts"
    M. Tamura, H. Tajima, K. Yakushi, H. Kuroda, A. Kobayashi, R. Kato and H. Kobayashi: J. Phys. Soc. Jpn. 60 (1991) 3861.
    Perturbation theory was applied for the first time to justify the dimer model. The infrared data were analyzed to give the interdimer transfer integrals and the Fermi surface.
  15. "Temperature Dependence of the Polarized Reflectance Spectra of the theta-Type of Bis(ethylenedithio)tetrathiafulvalenium Triiodide theta-(BEDT-TTF)2I3: Estimation of Band Parameters",
    M. Tamura, K. Yakushi, H. Kuroda, A. Kobayashi, R. Kato and H. Kobayashi: J. Phys. Soc. Jpn. 57 (1988) 3239.
    The two transfer integrals to describe the Fermi surface of this materials are directly estimated for the first time from the infrared data.

I can answer to basic questions on

  • Optical Properties of Conducting Organic Solid --- Drude-like Infrared Reflectivity due to Conduction Electrons in Low-Dimensional Bands
    1. Measurement and Analysis
    2. Effective Mass
    3. Geometry and Anisotropy of Two-dimensional Fermi Surface
    4. Tight-binding Band Analysis
    5. Electron-Molecular Vibration (Vibronic) Couplings
  • Magneto-Structural Correlations in Organic Radical Crystals --- Nitronyl Nitroxide Radicals etc.
    1. Preparation, Purification and Crystal Growth
    2. Molecular Design
    3. Magnetic Susceptibility --- Measurement and Analysis
    4. Magnetization Process and Spin Gap
    5. Electron Paramagentic Resonance and Magnetic Anisotropy
  • ...

I am interested in

  • Novel Magnetic Properties of Molecular Systems --- Quantum Effect and Its Breakdown, Crossover Phenomena etc.
  • Magnetic Anisotropy Induced by Charge and Spin-Orbital Couplings in f-Electron Systems
  • Molecular Conductors under High Pressure
  • Low-cost Measurement of Magnetic Susceptibility by RF techniques
  • Temperature Dependence of Hall Coefficients of Molecular Conductors --- Thermal Breakthrough of Fermi Surface, Unusually High Mobilities, Relation to Molecular Vibrations etc. (Collaboration with Dr. Naoya Tajima)
    ある種の有機導体でホール係数が6桁も温度変化する現象 --- 有効フェルミ面効果,異常に高い移動度,分子内振動との関係など(田嶋尚也博士との共同研究)
  • Unusual Conductivity of Molecular Conductors at High Temperatures (Bad Metals)
  • and so on

Recent Research Activities

  1. Molecular Conductors Containing Rare-Earth Ions (pi-f Composite Metals)
    含希土類有機導体(π-f 複合伝導体)

  2. Magnetic Susceptibility of [Pd(dmit)2] Salts --- Frustrated Spin-1/2 Heisenberg Antiferromagnets on Triangular Lattice

  3. "Complete Charge Separation" (Valence Transition) due to HOMO-LUMO Interplay
    A New Type Charge Separation in a [Pd(dmit)2] Salt
  4. VB order and Superconductivity in Frustrated 2D Quantum Spin Systems
    Frustration-Induced Valence-Bond Ordering in a New Quantum Triangular Antiferromagnet Based on [Pd(dmit)2]
    Frustrated crystal chills out -Cooling allows chemical compound to rearrange itself in a spin Peierls transition-
    「有機分子 [Pd(dmit)2]がつくる2次元三角格子量子反強磁性体のスピン一重項状態 −フラストレーションとスピンギャップ相−」,田村雅史,加藤礼三, 固体物理,42(2),133-140 (2007).