Rectifying property and giant positive magnetoresistance of Fe3O4∕SiO2∕Si heterojunction

Fe 3 O 4 ∕ Si O 2 ∕ Si heterojunction was fabricated by growing Fe3O4 film on an n-typed Si wafer with the native SiO2 buffer layer using the pulsed laser deposition. Transmission electron microcopic study shows the high quality of the heterojunction interfaces and the SiO2 layer is 2.5nm thick. This junction shows a backward diodelike rectifying behavior and an anomalously giant positive magnetoresistance (MR) for the large reverse bias voltages. The temperature dependence of MR shows a peak around the Verwey transition temperature with a maximum MR of 87% under a −2V bias voltage. The results were discussed by considering the band structure of the heterojunction and the effect of the reverse bias voltage.