Thermal enhancement of the antiferromagnetic exchange coupling between Fe epilayers separated by a crystalline ZnSe spacer
Résumé
We provide evidence for the existence of an antiferromagnetic coupling between iron epilayers separated by a wedge-like ZnSe crystalline semiconductor by magnetometric and ferromagnetic resonance experiments. The coupling strength of 46 mu J m(-2) for t(ZnSe) = 25 angstrom is strongly reduced as the barrier thickness is increased. The coupling increases linearly with temperature from 5 to 300 K, with a 5.5 x 10(-9) J m(-2) K-1 rate. Thermally induced effective exchange coupling mediated by spin-dependent tunnelling of electrons via localized mid-gap defect states in the ZnSe spacer layer appears to be the most plausible mechanism to induce the antiferromagnetic coupling.