Enhancement of magnetic properties by adjusted structure in Fe nanocrystalline films via annealing and applying high magnetic field at different film-formation stages

Abstract

To improve the magnetic properties of films applied in spintronic devices, this article explored the microstructure and magnetic properties of Fe nanocrystalline films via annealing and applying high magnetic field (HMF) during different film-formation stages. The results indicate that both annealing and HMF inhibited the sloping and overlapping of the columnar grains in the as-deposited film. Annealing promoted the formation of nanoparticles, while annealing with HMF arrayed the columnar grains along the direction of HMF. A chain arrangement with mixture columnar grains and nanoparticles was observed by combined film-growth HMF and annealing. Different-stage HMFs and annealing improved the particle size but suppressed the stain and surface roughness of the Fe films. The film-growth HMF and annealing both enhanced the saturation magnetization (Ms) of the Fe films. Especially, combined film-growth HMF and annealing obtained 10% larger Ms than Fe bulk. The low disordered structure, average grain size and grain shape anisotropy under film-growth HMF and annealing remarkably decreased the coercivity (by 91%) but increased the remanence ratio (by 67%) of films. However, annealing with HMF did not obviously improve the magnetic properties of Fe films. These indicated that film-growth HMF and annealing provide useful ways to adjust structure and enhance properties.