1992 Fiscal Year Final Research Report Summary
Magnetic properties and electronic structure of organic crystals.
| Project/Area Number |
02403001
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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 |
物理化学一般
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| Research Institution | ISSP, Univ. of Tokyo |
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Principal Investigator |
KINOSHITA Minoru Univ.of Tokyo,ISSP,Professor, 物性研究所, 教授 (40011530)
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| Co-Investigator(Kenkyū-buntansha) |
TAMURA Masafumi Univ.of Tokyo,ISSP,Research Associate(1991-1992), 物性研究所, 助手 (00231423)
SUGANO Tadashi Meiji-gakuin Univ.Associate prof.(1990) (60134657)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Magnetic properties / Organic ferromagnet / Spin quantum effect / p-NPNN / Nitronyl nitroxide / Magneto-structural correlation / 量子効果 |
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| Research Abstract |
The magnetic properties of TTF and BEDT-TTF complexes with MX_4 (M=Mn, Co, Cu; X=Cl, Br) and charge transfer complexes of TTF having an organic radical substituents were examined to see magnetic interaction between conduction electrons and localized electrons. In EPR experiments, g-shift with temperature has been observed in the BEDT-TTF-CoCl_4, BEDT-TTF-MnCl_4 and TTF-MnCl_4 systems. An indication of short range magnetic order was also found in the system of TTF-MnCl_4.2. The orthorhombic phase of p-nitrophenyl nitronyl nitroxide (p- NPNN) has been found to undergo a transition towards ferromagnetic ordered state at 0.6 K. This is the first example of bulk ferromagnetism in organic compound composed of light elements(H, C, N and O). The ferromagnetism has been comfirmed by the measurements of ac susceptibility, heat capacity, hysteresis curve and spontaneous magnetization below Tc. 3. Thecommon structural feature for ferromagnetic coupling has been deduced from the studies of magneto-structural correlation in about 20 derivatives of phenyl nitronyl nitroxide. 4. The magnetic properties of a biradical and a triradical based on nitronyl nitroxide, the ground spin states of which are triplet and quartet respectively, have also been studied to see the effect of competition between the intramolecular exchange interaction and intermolecular exchange interaction. In particular, the biradical showed very complex magnetic behavior accompanying crystal structure change with temperature and spin quantum effect.
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