2002 Fiscal Year Final Research Report Summary
Summary of research on anomalous magnetic properties associated with orbital ordering and fluctuations
| 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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| Keywords | multipole order / neutron scattering / uniaxial pressure / field-induced gap / filled skutterudite / metal-insulator transition / hidden order parameter / orbital degeneracy |
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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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