Abstract
Epitaxial magnetic tunnel junctions with electrodes of spinel-structure Fe3O4 and perovskite La0.7Sr0.3MnO3 have been fabricated and characterized. Spinel barrier layers of magnetic FeGa2O4 and nominally nonmagnetic Mg2TiO4 were used to provide a good interface with the more sensitive Fe3O4 electrode interface. Junction magnetoresistances (JMRs) of up to −11% at 60K and −26% at 70K were observed for FeGa2O4 and Mg2TiO4 barrier junctions, respectively. The JMR bias dependence and junction resistance versus temperature data indicate that a majority of the junctions are dominated by elastic tunneling below about 50mV and by inelastic hopping through the barrier at higher bias.