Epitaxial growth of half metal thin films on GaAs(100) for spin injection

We report epitaxial thin films of half metal Fe$_{3}$O$_{4}$ and Fe$_{3}$Si on the GaAs(100) buffer layer grown by \textit{in-situ} MBE method. With only one spin band at $E_{F}$, half metals are 100{\%} spin polarized and are considered as an ideal candidate for spin injection. Fe$_{3}$Si is a ferromagnet with a T$_{c}$ of 840K, and a cubic DO$_{3}$ structure almost perfectly lattice matched to GaAs (100) surface. Preliminary RHEED studies showed the attainment of (100) FeO$_{x}$ thin films epitaxially grown on (100) GaAs with an in-plane 45\r{ } rotation in matching the major crytstallographic axes. The crystallinity of FeO$_{x}$ depends significantly on oxygen partial pressure during growth, film thickness, and the surface may undergo decomposition during cooling process. The chemical composition of the FeO$_{x}$ film was determined by XPS analysis by fitting the Fe 2p spectrum with two components of Fe$^{2+}$ and Fe$^{3+}$. Low temperature magnetic and electrical transport measurements are now underway.