Electrical Spin Injection and Detection in Silicon Nanowires

We report on the electrical injection and detection of spin-polarized electrons from cobalt contacts into n-type Si nanowires through Al2O3 tunneling barriers. Analysis of local (2 terminal) and non-local (4 terminal) spin valve signals at 4 K on the same nanowire device using a standard spin-transport model suggests that high spin injection efficiency ( about 30{\%}) and long spin diffusion lengths (about 6 micron) are achieved for these nanoscale structures. These values compare favorably to those reported for spin transport devices based on comparably-doped bulk Si. The spin valve signals are strongly influenced by temperature, bias current and by the geometry of the ferromagnetic