Structural and magnetic properties of Fe–Al alloys: Ab initio studies

In the framework of density functional theory, the structural and magnetic properties of Fe$_100-x$Al$_x$ alloys (${5 \leq x \leq 25}$~at.\%) with the different structural order are investigated. Using the Korringa-Kohn-Rostoker Green's function method with a coherent potential approximation, the equilibrium lattice parameters, ground-state energy, and shear moduli for D0$_3$, B2, and A2 structures are calculated. For all structures, the optimized lattice constant increases while the shear modulus demonstrates a decreasing behavior with increasing Al content. The tetragonal magnetostriction constants are estimated by the torque method. The A2 and B2 structures provide a positive contribution to the tetragonal magnetostriction. With the help of Monte Carlo simulations of the Heisenberg model, the Curie temperatures are obtained in a wide concentration range.