Anomalous thermal expansion and magnetostriction of rare earth compounds under high pressure

Abstract

The thermal expansion coefficients of Kondo compounds, CeBe 13 and CeRh 2Si 2, and the magnetostriction of Tb 0.3Dy 0.7Fe 2(Terfenol-D) have been measured at high pressure. By simple analysis using thermodynamical relation, it is found that the density of state at the Fermi level and the Grüneisen parameters Γ of the Kondo compounds decrease rapidly with increasing pressure corresponding to the large pressure-induced enhancement of Kondo temperatures. An anomalous behaviour in the thermal expansion coefficients of CeRh 2Si 2 is observed at high pressure above T N . This anomaly is suggested as an origin of pressure-induced superconductivity. The giant magnetostriction (GMS) of Terfenol-D is found to be enhanced by applying hydrostatic pressure below 0.5 GPa but GMS decreases above it. These results are discussed briefly by comparing with the previous ones.