Photoinduced antiferromagnetic interlayer coupling in Fe/(Fe-Si) superlattices

We report photoinduced antiferromagnetic (AF) interlayer coupling in sputtered Fe/(Fe-Si) superlattices. The superlattices are intrinsically AF coupled at room temperature and become increasingly ferromagnetically coupled when cooled below 100 K, but the AF coupling is restored at low temperature by exposure to visible light of sufficient intensity (>10 mW/${\mathrm{mm}}^2$). These effects are due to charge carriers in the Fe-Si spacer layer which, when thermally or optically generated, are capable of communicating spin information between the Fe layers.