Magnetic Entropy Changes of SmMn₂Ge₂ under High Pressure

Abstract

In order to obtain the information about magnetic states of reentrant ferromagnet, SmMn₂Ge₂, we have studied the pressure effect on magnetocaloric properties by magnetization measurements under high pressures up to 1.2 GPa in the temperature range from 5 to 300 K. Using the Maxwell relation, we estimated the magnetic entropy change |ΔS_M| to be 0.65 JK⁻¹mol⁻¹ at T₁ (=100 K) and 0.53 JK⁻¹mol⁻¹ at T₂ (=150 K) under 0.1 MPa. By applying pressures up to 0.5 GPa, |ΔS_M(T₁)| is enhanced (2.0 JK⁻¹mol⁻¹), while |ΔS_M(T₂)| is slightly suppressed (0.4 JK⁻¹mol⁻¹). The obtained values of |ΔS_M| were discussed on the basis of a mean field theory using a two-sublattice model.