Hybrid perovskite-spinel magnetic tunnel junctions based on conductive ferrimagnetic NiFe2O4.

Ultrathin epitaxial films of NiFe2O4, when grown under specific conditions, show a large enhancement of their magnetic moment and electrical conductivity. This allowed us to use such layers as electrodes in magnetic tunnel junctions. In this paper, we report on the observation of a large tunnel magnetoresistance at low temperature in La2/3Sr1/3MnO3/SrTiO3/NiFe2O4 junctions. From these results we infer a spin polarization of up to 45% for NiFe2O4, which stays constant up to ∼300 K. NiFe2O4 can therefore be considered as an alternative to Fe3O4 as a high-temperature spin-polarized Fe oxide. Furthermore, our findings provide a way to design materials for spintronics based on the stabilization of nonthermodynamically stable magnetic phases of spinel oxides. [ABSTRACT FROM AUTHOR]