| Project/Area Number |
06452064
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 Molecular Science |
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Principal Investigator |
KANODA Kazushi Okazaki National Research Institute, Institute for Molecular Science, Associate Professor, 分子科学研究所, 助教授 (20194946)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAMOTO Atsushi Ochanomizu University, Department of Physics, Associate Professor, 理学部, 助手 (60251691)
NAKAZAWA Yasuhiro Okazaki National Research Institute, Institute for Molecular Science, Research A, 分子科学研究所, 助手 (60222163)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1995: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1994: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | NMR / isotope / organic conductors / organic superconductcrs / metal-insulator transition / low-temperature properfies / antiferromagnetic transition |
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| Research Abstract |
A series of organic systems, (BEDT-TTF)_2 X,have been investigated by ^<13>C-NMR.Comparison of the nuclear spin-lattice relaxation rate, conducting property and molecular arrangement indicates a close relationship between the molecular arrangement and manifestation of electron correlation. The metal/nonmetal phases in the isostructural kappa- (BEDT-TTF)_2 X systems, which are in the strong dimeric regime, are understood as highly correlated metals and insulators crossing the Mott transition. The deuterated Cu [N(CN)_2]Br salt is found to be situated in the critical region of the transition between the superconducting and antiferromagnetic phases.
For the superconducting phase (Cu[N(CN)_2]Br salt) situated near the Mott transition, the absence of coherence peak and a low-temperature T^3 -dependence of the nuclear spin-lattice relaxation rate suggest unconventional superconductivity with line nodes in gap parameter or highly anisotropic one. The low-temperature specific heat is consistent
… More
with the unconventional one in both temperatura and field dependence.
In order to investigate the electronic state of the metallic (DMe-DCNQI)_2 Cu, we prepared isotopeenriched DMe-DCNQI molecules where each site of=N-CN was substituted by ^<13>C or ^<15>N and performed ^<13>C and ^<15>N-NMR measurements for the Cu salt and the Li salt as a reference material of pi-electron system without hybridization. The shift and relaxation rate analysis demonstarated that the Cu salt is a multiband system due to the pi-d hybridization ; the spin susceptibility of the nonbonding pi band and the bonding pi-d band has opposite temperature dependence. On the other hand, (DI-DCNQI)_2 Ag, a new member in the DCNQI-Metal complexes, has been investigated by electrical resistance, magnetic susceptibility and ^1H-NMR measurements and found to be non-metallic with a charge gap of -490K but without spin gap. An antiferromagnetic ordering is evidenced at a low temperature. By ^<13>C-NMR,this system was found to show charge ordering below -200K,which indicates important role of the intersite Coulomb interaction, V. Less
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