| Project/Area Number |
62540268
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | Kyushu University |
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Principal Investigator |
TAKEDA Kazuyoshi Faculty of Technology, Kyushu University, 工学部, 助教授 (10029548)
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| Co-Investigator(Kenkyū-buntansha) |
URYU Norikiyo Faculty of Technology, Kyushu Univeisity, 工学部, 教授 (60037702)
DEGUCHI Hiroyuki Faculty of Technology, Kyushu University, 工学部, 助手 (30192206)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Frustrated systems / Magnetic triangular lattice / Spin liquid / New universality class / Low-temperature heat capacity / Ground state / 相転移 / 新しいユニバーサリティクラス / 三角格子反強磁性体 / フラストレーション / 磁気比熱 / 混合原子価結合 |
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| Research Abstract |
Information of the ground state and phase transition in frustrated magnetic systems has been obtained by the measurements of nuclear and electronic heat capacity, and magnetic susceptibility.
The spin reduction which reflects the magnetic phase at low temperatures is estimated to be 40% for spin s=3/2 of VX_2(X:Br,Cl). This value makes a significant difference when compared with the reduction of 70% obtained from the nuclear diffraction experiment with the time scale of the order 10^<-13> sec.. It is revealed that systematic and dynamical observations are necessary for understanding the ground state of frustrated systems.
The linear dependence of the heat capacity on low-temperatures is expected for the Fermi liquid in the resonating valence bond state. The heat capacity of VX_2, however, does not show the T^1 term. The crucial check of this is possible with the frustrated system with s=1/2. Not only the linear dependence of the heat capacity, but also any trace of the phase change is observed in the heat capacity measurements for LiNiO_2: the magnetic susceptibility measurements indicate the possibility of the successive phase transitions at T_<N1>=240K and T_<N2>=15K, which is a feature of the triangular antiferromagnet.
In the recent study of the superconductivity, the resonating valence bond state is stressed to play an important role in the CuO_2 plane with the electronic holes. We have begun investigating the resonating valence bond state also in the crystal of organic free radical which has some remarkable points when compared with inorganic compounds with the 3d electron. The magnetic behavior of the unpaired electron system ,triphenylverdazyi, is given as the first example.
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