Molecular-Orbital Model of Heat-Induced Effective Exchange Coupling in Magnetic Multilayers

Abstract

Heat-induced effective exchange coupling between two ferromagnets across a semiconductor spacer layer is described by the interaction of localized, weakly bound electron states which are situated at the two interfaces. These states overlap across the spacer layer and form large molecular orbitals. The energies of these orbitals depend on the spin configuration of the electrons 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.