Magnetoresistance of magnetite thin films grown by pulsed laser deposition on GaAs(100) and Al2O3(0001)

Magnetotransport properties of magnetite thin films deposited on gallium arsenide and sapphire substrates at growth temperatures between 473 and 673 K are presented. The films were grown by UV pulsed laser ablation in reactive atmospheres Of O-2 and Ar, at working pressure of 8 x 10(-2) Pa. Film stoichiometry was determined in the range from Fe2.95O4 to Fe2.97O4. Randomly oriented polycrystalline thin films were grown on GaAs(1 0 0) while for the Al2O3(0 0 0 1) substrates the films developed a (I 1 1) preferred orientation. Interfacial Fe3+ diffusion was found for both substrates affecting the magnetic behaviour. The temperature dependence of the resistance and magnetoresistance of the films were measured for fields up to 6 T. Negative magnetoresistance values of similar to 5% at room temperature and similar to 10% at 90 K were obtained for the as-deposited magnetite films either on GaAs(1 0 0) or Al2O3(0 0 0 1) (C) 2007 Elsevier B.V. All rights reserved.