First-principles electronic structure calculations were performed for defect and magnetic structures in FeCo. The compositional dependence curves of both formation energies and lattice parameters were obtained by calculations which involved super-cells of various sizes. The vacancy formation energies were calculated while taking into account the compositional dependence of the chemical potentials. It was found that antisite atoms compensated the deviation from the stoichiometric composition in both Fe-rich and Co-rich FeCo. The compositional dependence of the magnetic moments was well explained by the electronic structures of the antisite atoms. The vacancy formation energies obtained here exhibited better agreement with experimental data than did those previously reported.

First Principles Calculation of Defect and Magnetic Structures in FeCo. M.Mizuno, H.Araki, Y.Shirai: Materials Transactions, 2006, 47[11], 2646-50