Interface reflectivities and quantum-well states in magnetic multilayers

The reflection at the interface of a nonmagnetic and a magnetic layer represents the key quantity for the understanding of interlayer exchange coupling and quantum-well states (QWS). We give a general analysis of the scattering in one dimension in terms of scattering phase shifts and present analytical formulas for the reflection coefficients and the integrated density of states. We discuss the connection between reflectivity and QWS and calculate from first principles the reflection coefficient of a Cu Bloch electron at the (001) interface of fcc Fe, Co, and Ni layers of various, finite thicknesses. We discuss the effect of d resonances in the density of states of the magnetic layer on the reflectivity and the transition from finite to infinite layer thicknesses. We further demonstrate the close relation between the complex reflection coefficients and the width and position of QWS.