Structural and magnetization crossover in electrodeposited FeAl₂O₄ - effect of in situ oxidation

Amongst other spinels, iron aluminium oxide (FeAl₂O₄) exhibits exceptional chemical and physical properties. However, magnetic properties of FeAl₂O₄ still need further investigation. DC electrodeposition is used to deposit intermetallic Fe₃Al thin films. Oxidation time is varied from 0 to 20 min with a constant metallic layer deposition time of 10 min. Electrodeposited iron aluminium oxide thin films are annealed in the presence of 500 Oe applied magnetic field (MF) at 300 °C in a vacuum. Mixed structural phases, i.e. FeAl₂O₄ & χ-Al₂O₃, are observed at 5 min, 10 min and 15 min oxidation time. Whereas phase pure FeAl₂O₄ is observed at 20 min oxidation time. Magnetization loops show ferromagnetic behavior of iron aluminum oxide thin films with anisotropic nature for in-plane and out-plane configurations. The law of approach to saturation magnetization (LAS) is used to calculate magnetocrystalline anisotropy. Phase purity at 20 min oxidation time results in high saturation magnetization of 29.5 emu cm^-3 with a low value anistopy constant of 1.28 × 10⁸ erg cm^-3. Easy axis of magnetization is shifted from perpendicular to parallel at an oxidation time of 20 min. Results show that in situ oxidation of thin films for 20 min leads to structural and magnetization crossover from impure to phase pure FeAl₂O₄ thin films with a high value of magnetization.