Stress and magnetic properties in high moment FeN thin films

Abstract

Single layer FeN films with low coercivity and low residual stress were prepared on Corning 0211 glass and Si substrates using rf diode sputtering without postannealing. Substrates and a small amount of nitrogen in the film had a significant effect on the magnetic properties and residual stress of FeN films. The residual stress in the pure Fe films showed tensile characteristics due to thermal stress. The stress decreased with increasing N2/Ar flow ratio and passed a zero point at a flow rate ratio of ∼3.5%, accompanied with a low coercivity. The stress changed to compressive with further increasing nitrogen in the lattice. The tensile-to-compressive transition in residual stress can be explained by the increase in lattice constant in FeN films. The lattice constant increased with increasing nitrogen flow during deposition, which was probably due to more nitrogen incorporation in the bcc Fe lattice.