On the spin polarization at the Fe3O4/γ-Al2O3 interface probed by spin-resolved photoemission and spin-dependent tunneling

We report on two independent measurements of the spin polarization at the Fe3O4/gamma-Al2O3 interface. Fe3O4/gamma-Al2O3 (111) bilayers have been epitaxially grown by oxygen-assisted molecular beam epitaxy onto alpha-Al2O3 (0001) substrates and some were covered ex situ by a cobalt electrode. Spin resolved photoemission yield to a negative spin polarization (similar or equal to -40 %) while transport measurements on Fe3O4/gamma-Al2O3/Co magnetic tunnel junctions show a positive TMR, which suggest that the tunnel spin polarization at the Fe3O4/gamma-Al2O3 interface is positive. (c) 2007 Elsevier B.V. All rights reserved.