PLD of Fe3O4 thin films: Influence of background gas on surface morphology and magnetic properties

Ablation of Fe3O4 targets has been performed using a pulsed UV laser (KrF, λ = 248 nm, 30 ns pulse duration) onto Si(100) substrates, in reactive atmospheres of O2 and/or Ar, with different oxygen partial pressures. The as-deposited films were characterised by atomic force microscopy (AFM), X-ray diffraction (XRD), conversion electron Mössbauer spectroscopy (CEMS) and extraction magnetometry, in order to optimise the deposition conditions in the low temperature range. The results show that a background mixture of oxygen and argon improves the Fe:O ratio in the films as long as the oxygen partial pressure is maintained in the 10−2 Pa range. Thin films of almost stoichiometric single phase polycrystalline magnetite, Fe2.99O4, have been obtained at 483 K and working pressure of 7.8 × 10−2 Pa, with a high-field magnetization of ∼490 emu/cm3 and Verwey transition temperature of 112 K, close to the values reported in the literature for bulk magnetite.