Modification of magnetic properties of Pt/Co/Pt films by Ga+ Ion irradiation: focused versus uniform irradiation

30 keV Ga + irradiation-induced changes of magnetic and magneto-optical properties of sputtered Pt/Co/Pt ultrathin trilayers films have been studied as a function of the ion fluence. Out-of-plane magnetic anisotropy states with enhanced magneto-optical effects were evidenced for specific values of cobalt thickness and irradiation fluence. Results obtained after uniform or quasi-uniform focused ion beam irradiation on either out-of-plane or in-plane magnetized sputtered pristine trilayers are compared. Similar irradiation-induced magnetic changes are evidenced in quasi-uniformly focused ion beam or uniformly irradiated films, grown either by sputtering or molecular beam epitaxy. We discuss on plausible common mechanisms underlying the observed effects.