MAGNETORESISTANCE OF COBALT-GOLD MULTILAYERS WITH AN INCREASING NUMBER OF PERIODS

Co-Au multilayers, eight in all, with between two and nine cobalt layers, were produced together in UHV by thermal evaporation. All cobalt layers were identically thick (0.8 nm) with easy magnetisation axis perpendicular to the film plane. The (111) gold interlayer thickness of 2.2 nm corresponds to an antiferromagnetic coupling [1]. Kerr rotation magneto-optics and magnetoresistance measurements under perpendicular magnetic field revealed separate coercive fields for each of the cobalt layers. The plateaux between two coercive fields represent different magnetisation direction configurations that could be identified by the magnetoresistance measurements. An adapted Camley-Barnas modelling of the multilayers with up to six cobalt layers was conducted which agreed well with experimental results and further confirmed the magnetisation reversal order deduced by the magnetoresistance measurements.