Silicon is an ideal material for spintronics. Indeed, it exhibits among the longest spin relaxation times (more than microseconds at low temperatures), thanks to the weak spin-orbit coupling. Furthemore, a silicon spin field-effect transistor is a holy grail in the field, waiting to be realized. Both the electron spin resonance and the electric spin injection experiments have provided vital information about the spin physics in this technologically important semiconductor. In particular, we have now nice data on the temperature dependence of the spin relaxation time, from 50 K to room temperature. In the previous period of this SPP we have explained these data from theory, and developed a powerful electronic structure model for indirect optical transitions based on pseudopotentials and realistic electron-phonon coupling. In the extension we request funding for comprehensive and systematic calculations of the optical spin properties of bulk and heterostructure silicon, providing realistic picture of the Faraday effect in spin-polarized silicon. We will also compute and analyze the heterostructure dependent spin-orbit fields, considering silicon slabs and Si/Ge quantum wells, from first-principles calculations with the help of recently developed special pseudopotential techniques. We will also continue to work on the spin physics in silicon quantum dots, calculating the phonon-induced spin relaxation in single and two electron coupled dots formed in an electrostatically confined two-dimensional electron gas.
