Simultaneous pressure-induced magnetic and valence transitions in type-I clathrate Eu8Ga16Ge30

Takahiro Onimaru, Satoshi Tsutsui, Masaichiro Mizumaki, Naomi Kawamura, Naoki Ishimatsu, Marcos A. Avila, Shuhei Yamamoto, Haruki Yamane, Koichiro Suekuni, Kazunori Umeo, Tetsuji Kume, Satoshi Nakano, Toshiro Takabatake

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Abstract

We have performed X-ray magnetic circular dichroism (XMCD) and X-ray absorption spectroscopy (XAS) measurements at pressures up to 17 GPa for the clathrate Eu8Ga16Ge30 (Curie temperature T C = 36 K). The temperature dependence of the XMCD spectra agrees well with that of the DC magnetization at ambient pressure. The TC is gradually enhanced with increasing pressures up to 13.3 GPa, and the divalent state of the Eu ions with J = 7/2 remains stable, but at 17GPa the XMCD intensity is strongly suppressed and a spectral weight corresponding to the trivalent state of Eu ions (with no magnetic moment) appears in the XAS spectrum. The concurrent change from the type-I clathrate structure to an amorphous phase has been observed by X-ray diffraction experiment. We conclude that the amorphization of this compound induces the mixed valence state, which collapses the ferromagnetism.

Original languageEnglish
Article number013701
Journaljournal of the physical society of japan
Volume83
Issue number1
DOIs
Publication statusPublished - Jan 15 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Onimaru, T., Tsutsui, S., Mizumaki, M., Kawamura, N., Ishimatsu, N., Avila, M. A., Yamamoto, S., Yamane, H., Suekuni, K., Umeo, K., Kume, T., Nakano, S., & Takabatake, T. (2014). Simultaneous pressure-induced magnetic and valence transitions in type-I clathrate Eu8Ga16Ge30. journal of the physical society of japan, 83(1), [013701]. https://doi.org/10.7566/JPSJ.83.013701