Estimation of the Pressure Effect of the Absolute Saturation Magnetization of Au4Mn, Indium Heusler Alloy and MnSb by Forced Magnetostriction Measurement

The forced magnetostriction constants of the ferromagnetic alloys Au 4 Mn, Cu 2 Mn 1.2 In 0.8 and MnSb were measured up to a magnetic field intensity of about 20 kOe over a temperature range from liquid air temperature to room temperature. By means of thermodynamical relations, the pressure coefficient of the absolute saturation magnetization 1/σ 0 ·(dσ 0 /d p ) was found to be -3.7×10 -11 (cm 2 /dyne) for Au 4 Mn, -0.055×10 -11 (cm 2 /dyne) for Cu 2 Mn 1.2 In 0.8 and -0.59×10 -11 (cm 2 /dyne) for MnSb, respectively. From these results and a relation based on the molecular field theory, the pressure coefficients of the exchange interaction 1/ J ·(d J /d p ) are estimated to be 8.2×10 -11 (cm 2 /dyne) for Au 4 Mn, 0.44×10 -11 (cm 2 /dyne) for Cu 2 Mn 1.2 In 0.8 and 0.60×10 -11 (cm 2 /dyne) for MnSb, respectively. The dependence of the exchange interaction on lattice constant is discussed.