Investigation of the First-Order Magnetic Transformation in Mn3Pt

Abstract

The effect of composition on the first‐order transformation from triangular into collinear antiferromagnetic structure (AF‐AF transformation) occurring in ordered Mn₃Pt has been investigated on ternary Mn₃Pt_1−xRh_x and binary Mn_3+yPt_1−y alloys using x‐ray and neutron‐diffraction methods. On increasing the concentrations x and y an increase in both the Néel and the transition temperatures with a simultaneous decrease in the lattice parameter were observed. The magnetic moment of Mn remained the same irrespective of the concentration and the AF‐AF transformation. The results suggest the existence of a critical lattice‐parameter value at which the transformation occurs, like that observed for the Mn_2−xCr_xSb system.