Effects of chemical ordering and composition on the magnetic properties of disordered FeAl alloys

Recent studies have shown that FeAl alloys are promising candidate for magnetically patterned media owing to their disorder induced magnetism property at room temperature. In this paper, we have studied the effect of chemical ordering on the magnetic properties of FeAl alloys. At first we have calculated the magnetic exchange interactions in disordered FexAl1-x (50⩽x⩽65) alloys from first-principles theories. With these exchange interaction parameters, we carried out Monte-Carlo simulations with the resulting Ising Hamiltonian, onto which the alloy system was mapped and obtained the x-T phase diagram of the system. We have studied the effect of chemical ordering from a body-centered cubic (A2 phase) to an ordered cubic B2 phase in FeAl on the paramagnetic to ferromagnetic transition as a function of alloy composition and ordering fraction. We have also studied the behavior of hysteresis loop and coercive field as a function of alloy composition, temperature and ordering fraction.