Microstructure and electromagnetic performance of the FeCoAlON films tuned by N2 pressure during reactive pulsed laser deposition

Abstract

FeCoAlON films were fabricated by reactive pulsed laser deposition. The microstructure and electromagnetic properties have been investigated as a function of N2 pressure, which was varied from 0 to 5 mtorr. All the FeCoAlON films contains ultrafine FeCo nanoparticles isolated by nonmagnetic insulating layers. Those insulating layers ensure high electrical resistivity of the films and will be transformed from Al2O3 into AlN with increasing N2 pressure. The oxidation of Fe and Co can be effectively suppressed by introducing N2. The Fe tends to form amorphous iron nitrides at higher N2 pressures, leading to different magnetic response. Optimized electromagnetic properties can be achieved under 3 mtorr of N2, showing great potential in noise suppression application at high frequencies. Further increased N2 pressure to 5 mtorr leads to shrunken FeCo nanoparticles and thickened insulating layers due to the formation of nonmagnetic iron nitrides, giving rise to superparamagnetic response of the FeCoAlON thin film. Consequently, appropriate N2 pressure plays an essential role in inducing favorable microstructure and phase composition for enhanced electromagnetic performance.