2013 Fiscal Year Final Research Report
Modulated ferromagnetic structure in rare-earth clathrate compounds
| Project/Area Number |
23740275
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Condensed matter physics II
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| Research Institution | Hiroshima University |
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Principal Investigator |
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| Research Collaborator |
UMEO Kazunori 広島大学, 自然科学研究支援開発センター, 准教授 (10223596)
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| Project Period (FY) |
2011 – 2013
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| Keywords | 希土類クラスレート / ラットリング / 強磁性 / キャリアドープ / XMCD |
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| Research Abstract |
Eu clathrate Eu8Ga16Ge30 is a ferromagnet with TC=36 K. We examined relationship between rattling motion of the Eu guest atom and a modulated magnetic structure. The temperature dependence of the X-ray magnetic circular dichroism (XMCD) spectra agrees well with that of the DC magnetization at ambient pressure. At pressures up to 13.3 GPa, the divalent state of the Eu ions with J = 7/2 remains stable, but at 17 GPa the XMCD intensity is strongly suppressed and a spectral weight corresponding to the trivalent state of Eu ions appears in the X-ray absorption spectroscopy spectrum. The concurrent change from the type-I clathrate structure to an amorphous phase has been observed by X-ray diffraction experiment. In electron-doped systems, the temperature dependence of the saturated magnetization agrees with a mean-field calculation with a Heisenburg model. The results suggest that the modulated magnetic structure is probably attributed to the low carrier density.
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[Journal Article] Simultaneous Pressure-Induced Magnetic and Valence Transitions in Type-I Clathrate Eu_8Ga_<16>Ge_<30>2014
Author(s)
T. Onimaru, S. Tsutsui, M. Mizumaki, N. Kawamura, N. Ishimatsu, M. A. Avila, S. Yamamoto, H. Yamane, K. Suekuni, K. Umeo, T. Kume, S. Nakano, T. Takabatake
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Journal Title
J. Phys. Soc. Jpn
Volume: 83
Pages: 013701-1-4
DOI
Peer Reviewed
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[Journal Article] Nonmagnetic ground states and phase transitions in the caged compounds PrT_2Zn_<20> (T = Ru, Rh and Ir)2012
Author(s)
T. Onimaru, K. T. Matsumoto, N. Nagasawa, Y. F. Inoue, K. Umeo, R. Tamura, K. Nishimoto, S. Kittaka, T. Sakakibara, T. Takabatake
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Journal Title
J. Phys. : Condens. Matter
Volume: 24
Pages: 294207-1-5
DOI
Peer Reviewed
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