Ab initio calculations of the itneralyer exchange coupling of Fe-/Co-/Ni-layers in Cu(100)

摘要

Ab initio calcualtiosn for fcc Fe, Co and Ni layers in Cu(100) have been performed using a KKR-Green's function method for planar defects. The exchange coupling energy of magnetic bilayers was calculated from the single-particle energies wihtin the framework of the frozen potential approximation. The claculations revealed that for Ni the amplitude of the long and the short period is strongly reduced compared iwth Co and Fe. While the short period dominates the couplign for Ni and Co layers, the long period becomes important in the the case of Fe. The asymptotic behavior for large spacer thicknesses and the amplitudes of the different oscillation periods are discussed with the help of spin- and q_||-resolved density of states and the corresponding bulk band structures of the magnetic layers. For the longer period the minority bands of Ni-are sp-like and very similar to the Cu bands, while the corresponding Co bands contain a larger d-admixture. In contrast to this, in the case of Fe the Fermi level is situated in a band gap slightly below the DELTa_1-band.