Spin reorientation transitions in Pt/Co/Pt films under low dose Ga+ ion irradiation

A new route for tuning the magnetic anisotropy of ultrathin Co films by Ga+ ion irradiation is presented. The magnetic anisotropy of a Pt/Co(2.6 nm)/Pt film is first changed from in-plane to out-of-plane by uniform low dose Ga+ ion irradiation at 30 keV. When increasing the dose, a second spin reorientation transition towards the sample plane is also evidenced. This could be an elegant way to design magnetic nanowires with perpendicular anisotropy, embedded in an in-plane magnetized environment, either by uniform irradiation through a mask or focused ion beam. Tentative explanations
on the origin of these two successive spin reorientations are proposed.