Electron spin resonance studies on single crystalline Fe3O4 films

Abstract The effects of surface coating (Co and/or Co x O y ) on magnetic anisotropies in single crystalline Fe 3 O 4 films with different thickness that were epitaxially grown on MgO (1 0 0) substrate have been studied by electron spin resonance (ESR) technique. The angular dependent ESR spectra were analysed by using well-known SWR theory and the magnetic anisotropy parameters were deduced. The magnetic anisotropies are deeply affected from both film thickness and surface coating conditions. Magneto-crystalline cubic anisotropy (30 and 60 Oe for 110 and 2771 A thick films, respectively) is much smaller compared to its value for the bulk sample of the same compound ( H k =2 K 1 / M =460 Oe). The effective magnetization is influenced by the surface coating as well. The spectra for surface-coated films broaden especially for Co 3 O 4 -coated samples.