Exchange interaction and magnetic phase transition in layered Fe/Au(001) superlattices

Ab initio calculations for layered Fe/Au(001) superlattices with a set of c ollinear spin configurations are performed by means of the self-consistent full-potential linearized augmented-plane-wave method under the generalized gradient approximation. To study the finite-temperature magnetism of such superlattices, Monte Carlo (MC) simulations are carried out based on a Heis enberg model with the exchange parameters extracted from the ab initio tota l energies and a phenomenological anisotropy constant. It is argued that th e Curie temperature is rather insensitive to the anisotropy and is essentia lly determined by the ab initio exchange parameters. Due to the reduced coo rdination number of the magnetic atoms at interfaces, the Curie temperature obtained by this ab initio MC scheme decreases as decreasing of Fe layer t hickness governed essentially by Weiss' law. These results are discussed in connection with recent experimental and theoretical studies.