Strong Pressure Effect on the Curie Temperature of Itinerant-Electron Metamagnetic La(Fe_0.88Si_0.12)₁₃H_y and La_0.7Ce_0.3(Fe_0.88Si_0.12)₁₃H_y

Abstract

The initial pressure shift of the Curie temperature T_c for the first-order transition, dT_c⁄dP, for La(Fe_0.88Si_0.12)₁₃ becomes small after hydrogen absorption. In addition, the hydrogen absorption reduces the ratio of the volume change at T_c to the magnetization squared at T_c, Δω(T_c)⁄M(T_c)_F², suggesting the decrease of the magnetoelastic coupling constant κC_mv. On the other hand, dT_c⁄dP is enhanced by the partial substitution of Ce for La in connection with the change of the band structure. Consequently, dT_c⁄dP of La_0.7Ce_0.3(Fe_0.88Si_0.12)₁₃H_y is larger than that of La(Fe_0.88Si_0.12)₁₃H_y in a wide change of T_c.