Valley splitting and spin lifetime enhancement in strained thin silicon films
The electron spin properties are promising for future spin-driven applications. Silicon, the major material of microelectronics, also appears to be a perfect material for spintronic applications. The peculiarities of the subband structure and details of the spin propagation in ultra-thin silicon films in presence of the spin-orbit interaction and strain are investigated. The application of shear strain dramatically reduces the spin relaxation in such films. We investigate in detail, how spin injection in any arbitrary direction modifies the spin relaxation matrix elements, and finally the spin lifetime in the samples. We demonstrate a two-fold enhancement of spin lifetime, when spin is injected in-plane of the sample, compared to that, when injected along the perpendicular-plane direction. Keywords—Spin relaxation in silicon, spin-orbit interaction, valley-orbit interaction, spin injection, k · p model.