Information Processing with Pure Spin Currents in Silicon: Spin Injection, Extraction, Manipulation and Detection

We demonstrate that information can be transmitted and processed with pure spin currents in silicon. Fe/Al2O3 tunnel barrier contacts are used to produce significant electron spin polarization in the silicon, generating a spin current which flows outside of the charge current path. The spin orientation of this pure spin current is controlled in one of three ways: (a) by switching the magnetization of the Fe contact, (b) by changing the polarity of the bias on the Fe/Al2O3 (injector) contact, which enables the generation of either majority or minority spin populations in the Si, providing a way to electrically manipulate the injected spin orientation without changing the magnetization of the contact itself, and (c) by inducing spin precession through application of a small perpendicular magnetic field. Spin polarization by electrical extraction is as effective as that achieved by the more common electrical spin injection. The output characteristics of a planar silicon three terminal device are very similar to those of non-volatile giant magnetoresistance metal spin-valve structures