Annealing effect on the magnetic properties of evaporated CoCr thin films

Series of CoxCr(1-x) thin films have been evaporated under vacuum onto monocrystalline silicon substrate, x being atomic percent of cobalt. The thickness ranges from 17 to 220 nm, values measured by Rutherford backscattering spectrometry. The samples have been annealed under vacuum for one hour at 700 degrees C. The as deposited films show a hexagonal close packed (hcp) structure while the annealed films show both hexagonal close packed and face centered cubic (fcc) structures. While the as deposited films are under a compressive stress, the annealed films, on the contrary, are under a tensile stress. The hysteresis loops present the same features for the as deposited and annealed films concerning the in-plane and out-of-plane anisotropies. Nevertheless, the coercive field is strongly improved for the annealed films. Moreover, these latter films present very high values of the squareness. A squareness value up to 0.96 has been measured. All these results and others are analyzed and discussed.