Theory of spin relaxation and spin dynamics in silicon: from bulk to quantum dots.

Silicon has thus far found only limited application in spintronics. Electrical spin injection into silicon is yet to be proven and fabrication technology for silicon quantum dots with electron density controllable electrostatically by top gates lags behind similar technology for GaAs. Nevertheless, silicon is a spintronics material with which one has to count. Spintronics should be as closely related to the existing silicon information technology as possible, for integration purposes, and spin materials properties of silicon are superior to GaAs. Indeed, the weaker spin-orbit coupling in silicon leads to much smaller spin relaxa-tion rates, as well as to much weaker effective interface spin-orbit interactions. Furthermore, silicon can be isotopically purified to inhibit the hyperfine interaction which is a leading decoherence channel. The project will systematically evaluate spin relaxation in bulk silicon as well as in silicon lateral quantum dots, both single and coupled. Realistic calcu-lations will be performed to obtain impurity and phonon-induced spin relaxation in the bulk, at different donor doping levels and temperatures. Such calculations are particularly useful in the absence of systematic experimental studies. Theory of spin relaxation and spin dynamics in silicon quantum dots will be developed. Anisotropy of the spin relaxation rates as well as of couplings of the orbital and spin states to external microwave fields will be investigated in relation to possible applications of the silicon dots in spin-based quantum information processing.