Spin transport in nanoscale Si-based spin-valve devices.

We investigated the spin transport in nano-scale silicon (Si)-based spin-valve devices with Fe electrodes, MgO/Ge tunnel barriers, and a 20 nm-long Si channel. We observed a clear spin-valve effect when a magnetic field was applied in the film plane along and perpendicular to the Si channel transport direction. Systematic investigations of the bias voltage dependence, temperature dependence, and magnetic-field direction dependence of the magnetoresistance indicate that the observed spin-valve effect is governed by the spin transport through the nano-scale Si channel. The spinvalve effect remains observable up to 200 K. For the device with MgO/Ge tunnel barriers, with a bias voltage of 1.7V at 50K, the spin-dependent output voltage is 13 mV, which is among the highest values reported so far. [ABSTRACT FROM AUTHOR]