Injecting electrode controlled electronic transport across Fe3O4 film-Si interfacial structure

A study of electronic transport has been carried out across a half-metallic Fe3O4 film-nSi interfacial structure in CPP mode with an interfacial SiO2 layer of <5 nm. It has been measured with and without applied magnetic field along the plane of the interface between 25 K and 300 K to investigate the role of half-metallic Fe3O4 layer on the transport. The electronic transport has shown a distinct behaviour for the reverse bias in which injection takes place from metallic film of Fe3O4 to silicon than for the forward bias in which injection takes place from silicon to metallic Fe3O4 side. It has been found that the reverse bias current shows a tunnel transport, Verwey transition like feature and low temperature positive GMR, evidencing spin involved transport from Fe3O4 to semiconductor side. Whereas the forward bias current has not shown any of the above features but a thermionic controlled transport, showing a change of resistance with temperature as of semiconductor silicon. Thus, it has been found that the transport is controlled by physical properties of the injecting electrode. The study has shown that the transport below Verwey transition temperature (TV) for the Fe3O4 film interfacial structure is also related to its electronic spins. The observed GMR of ∼200% at low temperature (for reverse bias current only) has been discussed as the effect of electronic spin scattering. Our unique observations from simple measurements of CPP I-V across the interfacial structure of Fe3O4-nSi seem significant to reveal that the Verwey transition is related to spins of half-metallic Fe3O4.