Effect of mechanical alloying on the pressure dependence of the Curie temperature of Ni-20Â at% Mn alloy

AC susceptibility measurements in mechanically alloyed (MA) Ni-20 at% Mn were made under hydrostatic pressures up to 7.5 GPa. The results were compared with a bulk alloy made by the conventional method of melting. The Curie temperature decreased with pressure at the rate of −6.9 and −8.0 K/GPa in MA and the bulk alloy, respectively. The transition temperature to the reentrant spin glass state increased at the rate of 1.2 and 1.7 K/GPa in MA and the bulk alloy, respectively. The results were explained by assuming a Gaussian distribution of concentration fluctuation.