| Project/Area Number |
16510076
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanostructural science
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| Research Institution | Graduate School of Natural Science and Technology, Okayama University |
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Principal Investigator |
KAMBE Takashi Okayama University, Graduate school of natural science and technology, research, 自然科学研究科, 助手 (00277386)
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| Co-Investigator(Kenkyū-buntansha) |
OSHIMA Kokichi Okayama University, Graduate school of natural science and technology, professor, 自然科学研究科, 教授 (10114414)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | fullerene / pressure-induced phase transition / ferromagnetism / polymer / 軌道秩序 |
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| Research Abstract |
1.Pressure variation of lattice parameters and ferromagnetism in the fullerene ferromagnet α-TDAE-C_<60>
We have measured a pressure variation of lattice parameters in the ferromagnetic polymorphs, α-TDAE-C_<60> using the diamond anvil cell (DAC). We have found that the intrachain length along the nearest-neighbor C_<60> hardly depends on the pressure as compared with the lengths between chains. The compressibility along the b-axis (interchain direction) is estimated to be db/dP= - 0.042Å/kbar. Above the critical pressure Pc=0.6GPa, the X-ray photographs have been drastically changed, which should be related to the first-order structural phase transition to the high-pressure polymeric phase, however, we could not succeeded in solving the structure above Pc due to a limit in observed reflections.
We have used a cylinder-type high pressure cell, which was developed for the SQUID magnetometer, in order to clarify whether the bulk magnetism depends on the pressure. Both the saturation magnetization and the Curie temperature clearly depend on the pressure and suppressed with increasing the pressure. The Curie-like susceptibility above Pc indicates the localization of spin-carrier in the polymeric phase.
2.Antiferromagnetic phase transition in the polymorphic α'-TDAE-C_<60>
We have measured the low-frequency electron spin resonance and high-sensitive magnetic torque in order to clarify the low-temperature magnetic ground state of polymorphic α'-TDAE-C_<60>. It is found for the first time that the α'-phase undergoes an antiferromagnetic transition below 7K. Our structural study clearly indicates the structural deference between two polymorphs. Therefore, the magnetic measurements on the α'-phase establishes that the clear correlation between the magnetism and the low-temperature structure. The magnetism of the fullerene-based magnet strongly depends on the intermolecular contact between C_<60> and the degree of freedom of orbitals of C_<60>.
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