OSCILLATORY BEHAVIOR OF INTERFACE EXCHANGE COUPLING CAUSED BY FINITE CAPS OF VARIABLE THICKNESS

The effect of non-magnetic cap-layers on the periods and the amplitude s of the oscillations of interlayer exchange coupling (IEC) is studied theoretically using an ab initio spin-polarized surface Green functio n technique within a tight-binding linear muffin-tin orbital method an d the Lloyd formulation of the IEC. Applications are made to the free- electron like model as well as to Co/Cu/Co(0 0 1) trilayers with a cap interfacing vacuum through the dipole barrier. The results are analyz ed in terms of a discrete two-dimensional Fourier transformation which confirms a pronounced oscillatory behavior of the IEC with respect to the thickness of the cap-and the spacer-layers. The results are in ag reement with available experimental data as well as with predictions o f the electron confinement model of the IEC. Copyright (C) 1998 Elsevi er Science B.V.