Giant magnetoresistance effect in grain-type alloy thin films

FeCo-Ag thin films with a grain structure, in which the FeCo alloy and the Ag metal are mutually insoluble, were prepared by a vacuum deposition method. The maximum magnetoresistance (MR) ratio observed in these films was 13.0% at room temperature in the magnetic field region between -1 and 1 T. Here the features of the MR curve corresponded well with those of the magnetization curve. This indicates the appearance of a giant MR effect in such grain-type alloy thin films. Though the magnetic anisotropy field (Hk) associated with the MR characteristics that were obtained is extremely large (>1 T), proper annealing was found to be effective for decreasing the Hk value without causing a drop in the MR ratio.