UNAMBIGUOUS EVIDENCE OF OSCILLATORY MAGNETIC COUPLING BETWEEN CO LAYERS IN ULTRAHIGH-VACUUM GROWN CO AU(111)/CO TRILAYERS/

The first direct evidence of oscillatory coupling in Co/Au(111)/Co tri layers grown in ultrahigh vacuum is reported. For samples with identic al cobalt layer thicknesses, up to three peaks of magnetoresistance, c orresponding to antiferromagnetic coupling between the cobalt layers, are observed with increasing gold spacer layer thickness, t(Au). By gr owing trilayers with different cobalt coercive fields, a direct measur ement of both ferromagnetic and antiferromagnetic coupling as a functi on of t(Au) was possible. The experimental data are in good agreement with theoretical predictions.