Dependence of Magnetoresistance on Preparation Conditions and Annealing in Co/Cu Multilayers

The structure of sputter-deposited Co/Cu multilayer film depends strongly on such preparation conditions as the Ar gas pressure (PAr) and the substrate bias voltage (VB). For films deposited at VB=0 V, the interfaces were flat and the (111) plane orientation was good at low PAr. The (111) orientation was better for ¿30 V films than for 0 V films. The interface was flat at high PAr, in contrast with 0 V films. The giant magnetoresistance (GMR) depended heavily on the layer flatness, the film density, and the existence of crystal grains with an fcc (200) orientation. The effect of annealing on the film structure and GMR was also investigated. Annealing for 10 min. at 200°C in vacuum did not change the film structure very much, but the first GMR peak height of 0 V films decreased significantly, in contrast to the stable second GMR peak.