| Project/Area Number |
05402013
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Institute for Solid State Physics, University of Tokyo |
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Principal Investigator |
YASUOKA Hiroshi Institute for Solid State Physics, University of Tokyo, Professor, 物性研究所, 教授 (50026027)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Akihiko Institute for Solid State Physics, University of Tokyo, Research Associate, 物性研究所, 助手 (10228562)
UEDA Yutaka Institute for Solid State Physics, University of Tokyo, Associate Professor, 物性研究所, 助教授 (20127054)
IYE Yasuhiro Institute for Solid State Physics, University of Tokyo, Professor, 物性研究所, 教授 (30125984)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Electron correlation / Unusual metallic state / Nuclear Magnetic Resonance / Spin gap / Spin-charge separation / Spin-Peierls transition / Low dimensional compund / Oxide superconductors |
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| Research Abstract |
1.Cu compounds
High-T_c materials Anomalous magnetic behavior in metallic states is revealed by NMR study.
Antiferromagnetic spin fluctuation localized on Cu spins shows strong dependence on carrier concentration, temperature. A gap (-150K) in the spin excitation was observed at low carrier concentration. NMR and NQR results suggest spin-charge separation in metallic states.
K_3Cu_8S_6 (layr-type structure) With decreasing temperature, a successive transition, metal-CDW insulator-metal, occurs. The low temperature metallic phase is anomalous metal accompanied by CDW state.
CuS (layr-type) Magnetic excitation is understood in a scheme of quasi-particles in Fermi liquid with weak electron correlation.
CuGeO_3 (1D structure) Using single crystals grown by an FZ method, NMR study shows the orbital susceptibility and hyperfine interaction are attributed to a Cu^<2+> single ion in orthorhombic crystal field.
2.Non-Cu compounds
SrVO_3 (Perovskite-type) Spin-lattice relaxation rate (1/T_1) at V and O sites shows anomalous temperature dependence similar to that of Cu (1) site in YBCO.
CaVO_<3-delta> (Perovskite-type) Four phases were first identified with oxygen nonstoichiometry, delta.Electron correlation increases with delta, and spin-charge separation exists in some phases.
V_2O_3 Pseudo-spin gap behavior was observed in Knight shift (K) and 1/T_1 in a pressure-stabilized metallic phase.
LiV_2O_4 (Spinel-type) Li-and V-NMR revealed a magnetic excitation with heavy fermion-type, which is the first observation in 3d-transition metal compounds.
CaV_2O_5 (1D ladder-type) Spin-gap behavior similar to that of SrCuO_2 was observed. The gap was estimated to be 580K.
NaV_2O_5 Magnetic susceptibility obeys 1D AF Heisenberg model with J/K_B=280K.Spin-Peierls transition was observed at 34K,which i the highest transition temperature at present.
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