INTRINSIC AND HEAT-INDUCED EXCHANGE COUPLING THROUGH AMORPHOUS-SILICON

We show that ferromagnetic films separated by a spacer of amorphous Si are exchange coupled for Si thicknesses d(Si) less-than-or-equal-to 40 angstrom. For 14 angstrom < d(Si) < 22 angstrom we observe antiferromagnetic coupling. The coupling strength of approximately 5 X 10(-6) J/m2 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.