Abstract
Intrinsic and heat-induced exchange coupling exists between ferromagnetic films separated by non-magnetic semiconducting spacer layers. Magnetic coupling across thin amorphous layers of Si, SiO, Ge and Ge/Si heterostructures is described. Antiferromagnetic coupling occurs in a limited thickness range for Si and Si/Ge heterostructures, and ferromagnetic coupling is found for SiO, Ge, and certain thicknesses of Si and Si/Ge heterostructures. The coupling strength is very weak, of the order of a few 10−6 J/m2. It exhibits a pronounced temperature dependence with a positive temperature coefficient for both ferro- and antiferromagnetic couplings. The observations indicate that resonant tunneling through defect states in the spacer material mediates the exchange coupling.
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