As electron spin continues to be sought for exploitation in technological devices, understanding the spin’s coupling to its environment is essential.
This dissertation theoretically explores spin relaxation in two systems: the cubic zinc-blende and hexagonal wurtzite crystals.
First, bulk systems with the zinc-blende crystal structure are studied. A model that includes both localized and itinerant spins and their interaction successfully explains the observed phenomena.
When this model is applied to certain quasi-two-dimensional structures of the same crystal type, it succeeds again after the exciton and exciton-bound-donor spin species are introduced. For the first time a quantitatively accurate explanation of the strange temperature dependence in intrinsic (110)-GaAs quantum wells is given.
Second, the properties of the wurtzite crystal are studied in regards to their usefulness in spintronic devices. Research along these line in wurtzite is undeveloped in comparison to zinc-blende.
The theory of the D’yakonov-Perel’ and Elliott-Yafet spin relaxation mechanisms is developed.
n-ZnO is concentrated on in bulk systems. The impurities must be carefully considered when explaining the experimentally observed spin relaxation times; the presence of a deep donor and a shallow donor give rise to the observed phenomena.
Wurtzite quantum wells have properties that could be especially beneficial spintronic devices. The D’yakonov-Perel’ mechanism, which the dominant spin relaxation mechanism in the materials considered here, can be suppressed at low temperatures much more effectively than can be done in zinc-blende due to the difference in spin-orbit fields. Suppression of spin relaxation is also greater in wurtzite than in zinc-blende at room temperature due to the smaller spin-orbit coupling in the examined wurtzite semiconductors.
Finally, the role an external magnetic field plays in the interacting localized-itinerant spin picture is examined and used to explain a ‘spin beating’ phenomenon.