Uniaxial in-plane magnetic anisotropy of a CoPt thin film induced by ion irradiation

The mechanism for ion-induced uniaxial magnetic anisotropy of ferromagnetic CoPt thin films is investigated using x-ray diffraction and soft x-ray emission spectroscopy. When Co∕Pt multilayers 64nm thick are irradiated with 80keV Ar+ ions in an externally applied magnetic field, the magnetization of the ion-irradiated area shows a significant anisotropic angular dispersion in its hysteresis. Analysis of x-ray diffraction patterns and CoL3 emission spectra reveals that the formation of partially ordered (face-centered-tetragonal) CoPt phase and nonequivalent electronic hybridization between easy and hard axes causes the induction of a uniaxial magnetic anisotropy.