Perpendicular magnetic anisotropy of binary alloys: A total-energy calculation

Using the state-of-the-art relativistic full-potential version of the linear-muffin-tin orbital method we have performed ab initio calculations to study the magnetic properties of eight transition-metal binary alloys (FePt, CoPt, FePd, FeAu, MnPt₃, CoPt₃, VAu₄, and MnAu₄). Both the local-spin-density approximation (LSDA) and the generalized gradient approximation (GGA) to the exchange-correlation potential are used in the computation. The resulting spin and orbital magnetic moments of both approximations are similar and agree nicely with experiment, however, different values are found for the magnetocrystalline anisotropy energy (MCA), especially for MnPt₃, CoPt₃, and MnAu₄. For all the other alloys the difference between the MCA values calculated within LSDA and GGA is less than 1 meV. The volume shape anisotropy is found to be important for the FePd and MnPt₃ thick films, while it is negligible for the other binary alloys.