Pressure Dependence of Magnetic Transition Temperatures and Lattice Parameter in an Antiferromagnetic Ordered Alloy Mn₃Pt

Abstract

The ordered alloy Mn₃Pt is an antiferromagnet (AF) which shows an AF(D)–AF(F) transition at T_C=365 K below the Néel temperature of the F phase T_N(F) of 475 K. The pressure dependence of magnetic transition temperatures was studied up to 9.8 kbar. By application of pressure, T_N(F) decreases with dT_N(F)⁄dP=−7 K/kbar and T_C increases with dT_C⁄dP=14 K/kbar. Above 3.2 kbar, the antiferromagnetic F phase disappears, only the D phase appears and its Néel temperature T_N(D) increases with dT_N(D)⁄dP=5 K/kbar with further increase in pressure. The pressure dependence of lattice parameter was measured up to 52 kbar. The volume compressibility was obtained to be 0.9×10⁻³ kbar⁻¹. The magnetic transition temperature vs pressure and lattic parameter phase diagrams were determined.