Magnetic state effect upon the order-disorder phase transition in Fe-Co alloys: A first-principles study

We investigate the effect of global magnetization on the effective cluster interactions and order-disorder phase transition in FexCo1-x alloys. The effective cluster interactions are obtained by the screened generalized perturbation method as it is implemented in the exact muffin-tin orbitals formalism within the coherent potential approximation. The ordering transition from the high-temperature disordered body-centered cubic alloy to the ordered B2 phase is determined by Monte Carlo simulations. The calculated transition temperatures are in good agreement with the available experimental data for the effective interactions, which correspond to the experimentally observed magnetization at the order-disorder phase transition.