Positive giant magnetoresistance in a Fe3O4/SrTiO3/La0.7Sr0.3MnO3 heterostructure

A very large positive magnetoresistance (MR) has been discovered in a ${\mathrm{Fe}}_{\mathrm{3}}{\mathrm{O}}_{\mathrm{4}}{\mathrm{/SrTiO}}_{\mathrm{3}}\mathrm{/}$ ${\mathrm{La}}_{\mathrm{0.7}}{\mathrm{Sr}}_{\mathrm{0.3}}{\mathrm{MnO}}_{\mathrm{3}}$ heterostructure for the transport perpendicular to the layer planes and applied magnetic field in the film plane. The observed MR features do not show any obvious correlation with the hysteresis behavior of the ferromagnetic bilayers. A possible explanation of these results is given in terms of the relative differences in the majority and minority spin bands of the two ferromagnetic layers and the field induced modifications of domain structures therein.