| Project/Area Number |
14340107
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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 |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | TOKYO METROPOLITAN UNIVERSITY |
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Principal Investigator |
KOHGI Masahumi Tokyo Metropolitan Univ., Graduate school of science, Professor, 理学研究科, 教授 (30004451)
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| Co-Investigator(Kenkyū-buntansha) |
IWASA Kazuaki Tohoku University, Graduate school of science, Associate Professor, 大学院・理学研究科, 助教授 (00275009)
KUWAHARA Keitaro Tokyo Metropolitan University, Graduate school of science, Assistant, 理学研究科, 助手 (90315747)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥14,900,000 (Direct Cost: ¥14,900,000)
Fiscal Year 2004: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2003: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2002: ¥10,200,000 (Direct Cost: ¥10,200,000)
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| Keywords | CeP / Ce monopnictides / neutron diffraction / X-ray diffraction / low-carrier system / p-f mixing / magnetic polaron / X線解析 / 少数キャリアー系 / P-f mixing |
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| Research Abstract |
The purpose of the present research is to clarify the physics behind the novel phenomena exhibited by the low-carrier systems Ce-monopnictides by neutron scattering and X-ray diffraction. The main results of the project are as follows :
(1)We have revealed by neutron diffraction under high pressures that the magnetic state of CeP at the pressures above 3.2 GPa is ferromagnetic at low temperatures in spite that the magnetic phase diagram below about 3 GPa is very complex with long period magnetic structures with the periods of 9,8,7,6,5,4,3 Ce (001) planes with increasing pressure. We found also that the saturation magnetic moment of a Ce atom in the ferromagnetic state decreases with increasing pressure above 3.2 GPa. (2)We established by utilizing synchrotron radiation X-ray diffraction technique that CeP shows long period magnetic structures with the periods of 11,10,9,8 Ce (001) planes with increasing magnetic field up to 14 T. The result shows that the the magnetic field plays a similar role as the pressure on the appearance of the exotic magnetic states of CeP. (3)The X-ray diffraction experiments under high pressure revealed that the lattice constant of CeP increase in the ferromagnetic state at the pressures above about 3GPa whereas it decreases in the ordered state under pressure below 3 GPa. This fact together with the reduction of the ordered moment at the pressures above 3GPa indicates that 4f electron state of CeP changes its nature from an localized one to an itinerant one at the pressure above about 3 GPa.
These findings support the idea that the main parameter to govern the exotic properties of Ce-monopnictides is the carrier density in the system, and that the varieties of the exotic properties observed for Ce-monopnictides are predominantly due to the difference of the intrinsic carrier densities of the materials as well as to their change by applying external magnetic field or pressure.
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