| Project/Area Number |
11220201
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (B)
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | University of Tokyo (2000-2002)
Hokkaido University (1999) |
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Principal Investigator |
SAKAKIBARA Toshiro. Univ. of Tokyo, Inst. For Solid State Physics., Professor, 物性研究所, 教授 (70162287)
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| Co-Investigator(Kenkyū-buntansha) |
UEDA Kazuo Univ. of Tokyo, Inst. For Solid State Physics, Professor, 物性研究所, 教授 (70114395)
OHKAWA Fusayoshi.J Hokkaido Univ., Dept. of Physics, Professor, 大学院・理学研究科, 教授 (00107442)
AMITSUKA Hiroshi Hokkaido Univ., Dept. of Physics, Associate Professor, 大学院・理学研究科, 助教授 (40212576)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥47,500,000 (Direct Cost: ¥47,500,000)
Fiscal Year 2001: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2000: ¥12,000,000 (Direct Cost: ¥12,000,000)
Fiscal Year 1999: ¥32,100,000 (Direct Cost: ¥32,100,000)
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| Keywords | multipole order / neutron scattering / uniaxial pressure / field-induced gap / filled skutterudite / metal-insulator transition / hidden order parameter / orbital degeneracy / I軸応力効果 / ヘリカル構造 / スピン密度波 / f電子化合物 / 四重極転移 / 軸性圧力効果 / 高圧下中性子散乱 / 高圧下NMR / 低温磁化測定 / ミュオン緩和スペクトル / 磁気揺らぎ / 反強四重極転移 / 反強磁性転移 / 圧力効果 / 磁気相図 / 磁気八重極相互作用 / 磁化測定 |
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| Research Abstract |
In this project, we have investigated various phase transition phenomena and unusual magnetic properties originating from the orbital degrees of freedom in f electron systems, with special interest in the antiferro-quadrupolar (AFQ) transition, hidden order, and metal-insulator transitions.
We established the magnetic phase diagram of the typical AFQ ordering system PrPb3 and found that the transition temperature is enhanced in magnetic field depending on the field orientation. The results are successfully explained by magnetic interactions between field-induced antiferromagnetic moments in the AFQ phase.
In the phase IV of CexLa1-xB6, whose order parameter is still unknown, we performed magnetic measurements under uniaxial pressure and found that a strong magnetic anisotropy is induced by a pressure along the [100] direction. The results indicate that the order parameter in phase IV is intrinsically anisotropic, such as Gamma-5 type octupoles. In URu2Si2, neutron diffraction experiment under high pressure revealed that a non-magnetic order and an antiferromagnetic one coexist in the ordered phase of this system. Although the true order parameter of the non-magnetic phase is still unknown, the present results forces a constraint on the theoretical models of this system.
In the filled skutterudite compound PrRu4P12, the metal-insulator transition has been explained by the lattice distortion mechanism which remove the orbital degeneracy of a Gamma-3 non-Kramers doublet. The field-induced gap observed in Yb4As3 has been explained on the basis of alternating Dzyaloshinsky-Moriya interaction.
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