High spin polarization at room temperature in Ge-substituted Fe3O4 epitaxial thin film grown under high oxygen pressure

Abstract

Epitaxial thin films of room-temperature ferrimagnetic (Fe,Ge)3O4 were fabricated using pulsed laser deposition. Films with a single-phase spinel structure were grown under high oxygen pressures (0.01–0.6 Pa). The carrier transport across (Fe,Ge)3O4/Nb:SrTiO3 interface was studied to estimate the spin polarization of (Fe, Ge)3O4. Current–voltage curves of Fe2.8Ge0.2O4/Nb:SrTiO3 junction showed rectifying behavior even at 300 K whereas Fe3O4/Nb:SrTiO3 junction showed ohmic behavior. Calculations based on a model for a Schottky contact with a ferromagnetic component yielded a spin polarization of 0.50 at 300 K for Fe2.8Ge0.2O4, indicating its potential as a promising spin injector.