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

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, $P_{\mathrm{s}}$ $\sim$ 4.9 GPa at 300 K, decreases to $P_{\mathrm{s}}$ $\sim$ 3.6 GPa at 10 K. The decrease of $P_{\mathrm{s}}$ 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.

7 pages, 5 figures, submitted to J. Phys. Soc. Jpn

References in corpus (3)

• Odd-Parity Multipoles by Staggered Magnetic Dipole and Electric Quadrupole Orderings in CeCoSi
• NQR and NMR spectra in odd-parity multipole material CeCoSi
• Unusual Nonmagnetic Ordered State in CeCoSi Revealed by ${}^{59}$Co-NMR and NQR Measurements

Cited by in corpus (4)

• Observation of Electronic Structure Modification in the Hidden Order Phase of CeCoSi
• Mean-field Study of Antiferromagnetic and Antiferroquadrupolar Orderings in Tetragonal CeCoSi
• Structural Phase Transition in CeMnSi under Pressure and Comparative Structural Properties of $R$MnSi ($R$ = La, Ce, Pr, Nd)
• Kondo-Peierls transition with nonsymmorphic zone boundary gap formation