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arXiv · 2203.16817

Structural Phase Transition and Possible Valence Instability of Ce$-4f$ Electron Induced by Pressure in CeCoSi

Yukihiro Kawamura·Kakeru Ikeda·Alisha Nurshafiqah Binti Amat Dalan·Junichi Hayashi·Keiki Takeda·Chihiro Sekine·Takeshi Matsumura·Jun Gouchi·Yoshiya Uwatoko·Takahiro Tomita·Hiroki Takahashi·Hiroshi Tanida
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Abstract

X-ray powder diffraction and electrical resistivity measurements were performed on the tetragonal compound CeCoSi under pressure to elucidate the phase boundary of the pressure-induced structural transition and the change in the 4$f$ electronic state. The temperature-pressure phase diagram has been determined from the shift of the Bragg peaks and from the anomaly in the resistivity. The critical pressure, $P_{\rm s}$ $\sim$ 4.9 GPa at 300 K, decreases to $P_{\rm s}$ $\sim$ 3.6 GPa at 10 K. The decrease of $P_{\rm s}$ is due not only to the decrease in volume of the unit cell but also to an anisotropic shrinkage by cooling. When crossing the boundary to the high-pressure phase, the resistivity shows a significant drop to exhibit a metallic temperature dependence. The results of this study strongly suggest that the structural phase transition can be ascribed to valence instability of Ce-$4f$ electron.

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Yukihiro Kawamura, Kakeru Ikeda, Alisha Nurshafiqah Binti Amat Dalan, Junichi Hayashi, Keiki Takeda, Chihiro Sekine, Takeshi Matsumura, Jun Gouchi, Yoshiya Uwatoko, Takahiro Tomita, Hiroki Takahashi, Hiroshi Tanida. 2022-03-31. Structural Phase Transition and Possible Valence Instability of Ce$-4f$ Electron Induced by Pressure in CeCoSi. https://doi.org/10.7566/jpsj.91.064714

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