Magnetic modifications of thin CoFe films induced by Xe+-ion irradiation

We have investigated magnetic field assisted implantations of 200 keV Xe-ions in 30-90 nm thick Fe50Co50 alloy films on Si substrates at ion fluences of up to 1.3 x 10(16) cm(-2). Longitudinal magneto-optic kerr effect measurements at room temperature suggest that the coercivity of the films first decreases for increasing ion fluence, while the magnetic remanence develops as a superposition of fourfold and twofold uniaxial anisotropies. Higher Xe-ion fluences increase the density of pinning centers therefore causing slight increases of the coercivity and of the magnetostrictive anisotropy. Lattice expansion and ion-induced grain growth were measured parallel to MOKE by X-ray diffraction. (C) 2003 Elsevier B.V. All rights reserved.