Magnetic Properties of Fe-Co Thin Films Deposited by Ion Beam Sputtering

Fe-Co thin films were formed on slide glass by ion beam sputtering, and their magnetic properties were investigated for various compositions, substrate temperatures and annealing conditions. The bcc structure films deposited at low temperatures received a compressive stress from substrates, which decreased and changed to a tensile stress as the substrate temperature was raised, caused by accelerated crystal grain growth. Large saturation magnetizations, in excess of 20 kG, were obtained. However, films formed on unheated substrates have considerable Hk¿ and Hc values, which decreased as the substrate temperature increased. Vacuum annealing had an effect similar to that of substrate heating. It seems that the perpendicular magnetic anisotropy energy is mainly caused by the stress induced magnetic anisotropy.