EXCHANGE COUPLING OF FERROMAGNETIC LAYERS ACROSS NONMAGNETIC INTERLAYERS

In order to obtain the interlayer exchange coupling constant A12 as a function of the interlayer thickness d0 in magnetic sandwich structures we have measured the frequencies of the low lying spin wave modes by means of Brillouin light scattering. A computer fit is then applied which yields values for A12. This way we have determined A12 as a function of d0 for Fe/Cu, Fe/Ag, Fe/Au, Fe/V, Co/Pt, Co/Cu and Co/Y. Generally A12 decreases exponentially with increasing d0. In some cases we find an interesting dependence on the growth conditions, like e.g. crystallinity. Interlayers with good epitaxial growth decouple faster than polycrystalline ones. We report also on an experimental method which we have developed to facilitate these experiments: for the investigation of A12 as a function of d0 we use sandwich structures with wedge formed interlayers. A whole range of d0 can then be studied on one sample.