A theoretical study of interfacial structure of Co/Cu and Co/Pd multilayers

The electronic structures and energies of Co/Cu and Co/Pd multilayers with abrupt or mixed interfaces have been calculated using the linear muffin-tin orbital method in the atomic sphere approximation. The mixed interface is modelled by exchanging atoms between Co layers and Cu (Pd) layers. The calculated total energies of Co/Cu multilayers with mixed interfaces are higher than those of Co/Cu multilayers with abrupt interfaces. The calculated total energies of Co/Pd multilayers with mixed interfaces are lower than those of Co/Pd multilayers with abrupt interfaces. Stable interface structure appears to be abrupt in Co/Cu multilayers and mixed in Co/Pd multilayers, as revealed by experimental observations. Total-energy differences between the multilayer with abrupt interfaces and the multilayer with mixed interfaces are caused by Co 3d-band narrowing for Co/Cu multilayers and Pd spin polarizations for Co/Pd multilayers.