Magnetic properties of Fe3O4 thin films grown on different substrates by laser ablation

Magnetite thin films have been grown onto (1 0 0)Si, (1 0 0)GaAs and (0 0 0 1)Al2O3, at substrate temperatures varying from 473 to 673 K, by UV pulsed laser ablation of Fe3O4 targets in reactive atmospheres of O2 and Ar, at working pressure of 8 10 2 Pa. The influence of the substrate on stoichiometry, microstructure and the magnetic properties has been studied by X-ray diffraction (XRD), conversion electron Mo¨ssbauer spectroscopy (CEMS) and magnetic measurements. Magnetite crystallites, with stoichiometry varying from Fe2.95O4 to Fe2.99O4, are randomly oriented for (1 0 0)GaAs and (1 0 0)Si substrates and exhibit (1 1 1) texture if grown onto (0 0 0 1)Al2O3. Interfacial Fe3+ diffusion, which is virtually absent for (1 0 0)Si substrates, was found for both (0 0 0 1)Al2O3 and (1 0 0)GaAs, with some deleterious effect on the subsequent microstructure and magnetic behaviour.