| Project/Area Number |
16340105
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | Kobe University |
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Principal Investigator |
WADA Shinji Kobe University, Faculty of Science, Professor, 理学部, 教授 (00031360)
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| Co-Investigator(Kenkyū-buntansha) |
MITO Takeshi Kobe University, Faculty of Science, Assistant Professor, 理学部, 助手 (70335420)
HARIMA Hisatomo Kobe University, Faculty of Science, Professor, 理学部, 教授 (50211496)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥16,300,000 (Direct Cost: ¥16,300,000)
Fiscal Year 2006: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2005: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2004: ¥10,700,000 (Direct Cost: ¥10,700,000)
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| Keywords | strongly correlated electron system / quantum multi-electron state / quantum critical point / non-Fermi liquid / Yb-based compound / NMR / 多極子秩序 / 重い電子系 / 充填スクッテルダイト / 四極子秩序 / 磁気秩序 / 核磁気共鳴 |
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| Research Abstract |
In Yb-based compounds, the f electron level is rather less broadened than in the Ce case, that results in some exotic phenomena such as valence fluctuations, large orbital degeneracy, and higher-order multipolar ordering which can not be understood by simple electron-hole analogy. We have carried out experimental studies on Yb-based 114 series compounds and related ones, and successfully deduced important information described below to understand the underlying issues.
Field-tuning of Yb-based antiferromagnetic compounds to the quantum critical point
(1) The electrical resisitivity and NMR measurements on the heavy fermion compound YbAuCu4 provided evidence that the system can be driven from the originally antiferromagnetically ordered state to a nonmagnetic Fermi liquid state through the quantum critical point in fields close to 〜13kOe through. Temperature and field participating in the quantum critical phenomena are about one order higher in energy than those of YbRh2Si2 that has been
… More
intensively studied as only one non-Fermi liquid material among the Yb-based compounds.
(2) Heavy fermion filled-skutterudite compound YbFe4P12 has the quantum critical point in field less than 1 kOe, and exhibits the non-Fermi liquid-like behavior at rather high temperatures below〜10K.
Evolution of electronic states associated with approaching the quantum critical point by applying external pressure
(3) The first-order valence transition of YbInCu4 is completely suppressed with applying pressures above 2.4GPa, and the compound was found to transform into a ferromagnetically ordered ground state below 2.5 K. A temperature-pressure phase diagram for pressures up to 27GPa was established.
(4) Heavy fermion compound YbCu5 is shown to have the quantum critical point near 5GPa, and NMR measurements up to 2.5GPa exhibited that the localized properties of f electrons increases with pressure.
Experimental evidence for multipolar orderings
(5) The mixed-typed quadrupolar ordering in YbSb with Kramers doublet CEF ground state was evidenced by measuring the isotope effect on the Sb NMR linewidth.
(6) TmTe is shown to exhibit a multipolar (probably octupolar) ordering at 〜20K, in addition to the well know quadrupolar order at 1.6K. Less
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