Intrinsic and Heat-Induced Exchange Coupling through Amorphous Silicon

Abstract

We show that ferromagnetic films separated by a spacer of amorphous Si are exchange coupled for Si thicknesses ${d}_{\mathrm{Si}}\ensuremath{\le}40$\AA{}. For $14\AA{}<{d}_{\mathrm{Si}}<22\AA{}$ we observe antiferromagnetic coupling. The coupling strength of approximately 5 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$ J/${\mathrm{m}}^{2}$ is strongly temperature dependent with a positive temperature coefficient. We suggest that localized electronic defect states in the gap of amorphous Si mediate the exchange interaction. The particular coupling mechanism encountered here also works with noncrystalline ferromagnetic layers.