Microstructure and magnetic properties of FeCoN thin films

Abstract

Effects of nitrogen contents and substrate temperatures to the microstructure and magnetic properties of the FeCoN films have been investigated. According to the TEM and x-ray Scherrer’s equation analyses, we found that the grain size of films with substrate temperature below 200 °C is roughly about 13 nm, however, it increases very fast for films with substrate temperature above 300 °C. N content in the films is saturated to 30 at. %, as N2 flow ratio N2/(Ar+N2) is higher than 5 vol. %. From the magnetization studies, we have found that the saturation magnetization 4πMs of the optimum samples (with the substrate temperature near 200 °C) is 23.9 kG. The improvement of the magnetic properties is attributed to the combination of α-Fe with N to form the high magnetic moment FeN phases.