| Project/Area Number |
06452050
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Tokyo Metropolitan University (1995)
Tohoku University (1994) |
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Principal Investigator |
KOHGI Masahumi Tokyo Metropolitan University, Department of Physics, Professor, 理学部, 教授 (30004451)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Takashi Tohoku University, Department of Plapics, Professor, 大学院・理学研究科, 教授 (30004344)
IWASA Kazuaki same as above Assistant, 理学部, 助手 (00275009)
高橋 博樹 東大, 物性研, 助手 (80188044)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥8,700,000 (Direct Cost: ¥8,700,000)
Fiscal Year 1995: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1994: ¥7,600,000 (Direct Cost: ¥7,600,000)
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| Keywords | low-carrier system / charge ordering / heavy electrons / Kondo effect / magnetic polaron / neutron scattering / CeP / Yb_4As_3 / 強相関電子系 / セリウム化合物 / 磁気構造 / 磁気ポ-ロラン |
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| Research Abstract |
The purpose of this project is to study the unusual properties of the low carrier systems CeP and Yb_4As_3 by means of neutron scattering. The results are as follows :
1.CeP
CeP shows unusual magnetic phase diagrams under magnetic field as well as under high pressure. It shows also typical dense-Kondo-effect like transport anomalies. Our neutron scattering studies established the magnetic phase diagrams for the magnetic field below about 6 T and for the pressure below about 2 GPa. The obtained magnetic phase diagrams are quite novel and unique. In order to explain the phase diagrams, it is necessary to take into account the fact of the low carrier density in this system. The magnetic polaron model gives the most plausible picture to understand the system.
2.Yb_4As_3
Yb_4As_3 undergoes structural phase transition at about 290K,which was claimed to be that of a charge ordering. The compound shows also heavy electron anomalies at the low temperatures in spite of its extremely low carrier density of the order of 10^<-3> per formula. Our polarized neutron study proved directly the ordering of Yb^<2+> and Yb^<3+> in this material at low temperatures. The inelastic neutron scattering studies revealed the existence of spin excitations typical of a one-dimensional antiferromagnet. They are ascribed to the one-dimensional configuration of the Yb^<3+> ions caused by the charge ordering. There is also anomalous magnetic response other than the one-dimensional spin excitations. These facts indicate that the heavy electron anomalies in this system are strongly related with the Mott-transition-type change of the electronic state caused by the charge ordering.
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