Modification of magnetization ordering in Pt/Co/Pt trilayers depending on the scanning direction of a focused ion beam

•Pt/Co/Pt trilayers were irradiated quasi-uniform with FIB.•Irradiations were done by square spiral scanning.•Out-of-plane magnetization was observed for two fluence ranges.•Easy axes are inclined to the plane and perpendicular to the fast scanning direction. Focused ion beam (FIB) irradiation was applied to an ultrathin Pt/Co/Pt film to create micrometer-sized, square-shaped regions with perpendicular orientation of magnetization embedded in an in-plane magnetized environment. The FIB parameters like ion fluence and scanning direction are used to control the magnetic properties of the irradiated areas. We have studied the magnetic and magnetooptical properties in the irradiated areas as a function of ion fluence by means of component selective magnetooptical Kerr microscopy that measures separately pure polar and pure longitudinal components of magnetization. Two fluence ranges that induce perpendicular magnetization components were observed. In the higher fluence range, four regions with independently inclined out-of-plane magnetization, depending on FIB fast scan direction, and an unexpected magnetic domain structure were distinguished inside the squares irradiated by FIB.