ANTIFERROMAGNETIC INTERLAYER EXCHANGE COUPLING ACROSS AN AMORPHOUS METALLIC SPACER LAYER

By means of magneto-optical Kerr effect we observe for the first time antiferromagnetic coupling between ferromagnetic layers across an amor phous metallic spacer layer. Biquadratic coupling occurs at the transi tion from a ferromagnetically to an antiferromagnetically coupled regi on. Scanning tunneling microscopy images of all involved layers are us ed to extract thickness fluctuations and to verify the amorphous state of the spacer. The observed antiferromagnetic coupling behavior is ex plained by RKKY interaction, taking into account the amorphous structu re of the spacer material.