Magnetic Properties of Europium: Pressure and Impurity Effects

A study has been made of the magnetic properties of europium in the vicinity of the transition temperature Tt as functions of hydrostatic pressure. A marked drop in the moment, consistent with a first-order transition, is observed at atmospheric pressure, but the sharpness of this transition decreases at higher pressures. The variation of Tt with pressure is nonlinear above 4 kbar, with ΔTt/ΔP=0.45°±0.03°K/kbar in the limit P→0. This value corresponds, via the Clausius-Clapeyron relation, to twice the volume change previously estimated on the basis of direct thermal-expansion measurements. In addition, it is found that dθ/dP