Magnetoresistance Of Magnetite Thin Films Grown By Pulsed Laser Deposition On Gaas(1 0 0) And Al_2o_3(0 0 0 1)

摘要

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 × 10~(-2) Pa. Film stoichiometry was determined in the range from Fe_(2.95)O_4 to Fe_(2.97)O_4. Randomly oriented polycrystalline thin films were grown on GaAs(1 0 0) while for the Al_2O_3(0 0 0 1) substrates the films developed a (1 1 1) preferred orientation. Interfacial Fe~(3+) 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 ～5% at room temperature and ～10% at 90 K were obtained for the as-deposited magnetite films either on GaAs(1 0 0) or Al_2O_3(0 0 0 1).