Molecular-orbital model of heat-induced effective exchange coupling in magnetic multilayers

Heat-induced effective exchange coupling between two ferromagnets across a semiconductor spacer layer is described by the interaction of localized, we akly bound electron states which are situated at the two interfaces. These states overlap across the spacer layer and form large molecular orbitals. T he energies of these orbitals depend on the spin configuration of the elect rons and therefore determine the exchange coupling. Thermal repopulation of the levels yields a positive temperature coefficient of the coupling. The results are found to well reproduce the experimental observations.