Calculation of the Magnetic Properties for fcc Fe–Ni Alloys

The high-field susceptibility, local moments, the asphericity of the magnetic moments, the low temperature specific heat coefficient and the coefficient of T 2 dependence of the magnetization are calculated for fcc Fe–Ni alloys in the coherent potential approximation. The difference between the band widths of fcc Fe and Ni is taken into account. The subbands of d -electrons with t 2 g and e g symmetries, which are deduced from the calculated energy bands for Ni and fcc Fe in the interpolation scheme, are used. The calculated results show a good agreement with the experimental results except the Invar region. It is shown that the first-order transition from the ferromagnetic to paramagnetic state occurs at about 30 at% Ni, where the magnetization vanishes suddenly, and the high-field susceptibility is not so large as compared with the observed results.