Interfacial characteristics of a Fe 3 O 4 ∕ Nb ( 0.5 % ) : Sr Ti O 3 oxide junction

The temperature dependent Schottky diode characteristics of epitaxial junctions between Nb : Sr Ti O 3 (Nb concentrations: 0.5%) and Fe 3 O 4 are studied. Epitaxial thin films of Fe 3 O 4 were grown on Nb : Sr Ti O 3 substrates by pulsed laser deposition technique. The films and heterointerfaces were characterized by x-ray diffraction, Z -contrast transmission electron microscopy, magnetic susceptibility, four-probe in-plane resistivity, and the temperature dependent junction current-voltage ( I - V ) characteristics. The nonlinear nature of the characteristics is analyzed within the framework of thermionic emission theory. Junction parameters such as the Schottky barrier height ( ϕ B ) and ideality factor ( η ) are extracted. The temperature evolution of these parameters shows interesting and systematic trends, with remarkable changes near the Verwey transition ( T V = 120 K ) . The magnetic field dependence of I - V characteristic data is also recorded and a spin polarization of ∼ 80 % is estimated for the magnetite electrode.