Spin-filter effect in magnetite nanowire.

Spin-dependent electron transport in individual magnetite (Fe3O4) nanowires contacted with normal metallic electrodes was investigated. Such a configured device demonstrated a spin-filter effect, that is, only the minority spin carriers can transport through the magnetite nanowire due to its negative spin polarization. An anomalous positive magnetoresistance approximately 7.5% is observed at room temperature. Moreover, the magnetoresistance can be controlled via bias voltage.