Crystalline γ-Al2O3 barrier for magnetite-based magnetic tunnel junctions -: art. no. 012509

We report on the elaboration and physical properties of fully epitaxial Fe3O4/Al2O3 bilayers to be included in magnetic tunnel junctions. Uncovered Fe3O4(111) single layers and bilayers were epitaxially grown onto sapphire (0001) substrates. Appropriate growth conditions lead to a stoichiometric Fe3O4 layer both at the Fe3O4/Al2O3 interface and on the whole thickness, as checked by in situ x-ray photoelectron spectroscopy and by the observation of the Verwey transition, respectively. Transmission electron microscopy demonstrates the epitaxial growth of a gamma-Al2O3 layer on top of Fe3O4(111), which insulating properties have been monitored by conductive tip atomic force microscopy. (C) 2005 American Institute of Physics.