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 Mn3Pt1−xRhx and binary Mn3+yPt1−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 Mn2−xCrxSb system.