INTERLAYER MAGNETIC COUPLING IN TRANSITION-METAL MULTILAYERED STRUCTURES

The magnetic coupling of two layers of Fe through an intervening layer of Cr as a function of the Cr layer thickness has been computed. By including both RKKY and superexchangelike interactions between planes of Fe, and accounting for the surface roughness of the interfaces, the experimentally observed oscillations in the coupling between Fe layers as a function of Cr layer width could be reproduced. The predominance of antiferromagnetic coupling reflects the dominance of superexchange over RKKY exchange and is a consequence of the position of the Fermi level of Cr in a minimum between peaks in the density of states. This condition can be used to explain similar behavior in Co/Ru and to identify other possible transition metal systems for which this behavior may be observed.