Heat-induced antiferromagnetic coupling in multilayers with ZnSe spacers

Two ferromagnetic films separated by an amorphous semiconducting spacer are exchange coupled across the spacer layer. The coupling is reversibly tempe rature dependent with a positive temperature coefficient. As spacer materia l we use amorphous ZnSe which is a compound semiconductor and find heat-ind uced antiferromagnetic coupling in striking similarity to amorphous Si and Ge. In an Fe/alpha-ZnSe/Fe trilayer with spacer thickness between 18 Angstr om and 22 Angstrom the coupling is antiferromagnetic with a positive temper ature coefficient. At slightly larger thicknesses between 22 Angstrom and 2 5 Angstrom we find a reversible transition from ferromagnetic coupling at l ow temperatures to antiferromagnetic coupling at higher temperatures upon h eating. We discuss the reversibly heat-induced effective exchange coupling in terms of localized defect states in the band gap in the vicinity of the Fermi energy. [S0163-1829(99)04230-7].