Influence of substrate and ion irradiation on the magnetic properties of laser-deposited CoFe films

Highly textured FeCo thin films have been prepared by pulsed laser deposition on Si(1 0 0) and MgO(1 0 0) single crystals. The influence of the microstructure on the magnetic properties has been studied using the magneto-optical Kerr effect and vibrating sample magnetometry. The in-plane coercivity of the films deposited on Si and MgO was 28 Oe and 12 Oe, respectively. A fourfold in-plane magnetic anisotropy has been observed for a film deposited on MgO(1 0 0), in contrast to the isotropic pattern of the film deposited on Si. The films have then been irradiated under an in-plane magnetic field of 104 Oe by 40-keV Ne- and 200-keV Xe-ions, at a fluence of 1 × 1015 ions/cm2. For Xe-ions, the film deposited on Si(1 0 0) developed a twofold magnetic anisotropy, while the film on MgO exhibited only slight changes of the fourfold anisotropy.