Spin dynamics in semiconductor heterostructures

This thesis presents experimental investigations of the electron spin dynamics (i.e. the spin relaxation rate, This thesis presents experimental investigations of the electron spin dynamics(i.e. the spin relaxation rate, Γ s , and the g -factor, g * ) inGaAs/ AlGaAs based semiconductor heterostructures and the effect of symmetry breaking perturbations such as; an applied external electric field, shear strain or graded alloy composition in the barriers. Spin-polarised electron populations are generated and detected using optical methods. Quantum wells grown on a (001) zinc-blende substrate display isotropic inplane spin dynamics. The above perturbations act to lower the symmetry and therefore the spin dynamics are allowed to show in plane anisotropy. However, the microscopic origin of the anisotropy of Γ s is different to that of g * . This thesis contains a full study of the anisotropy of both Γ s and g * for all of the above perturbations. This reveals the microscopic effects on the band edges of the perturbations.It has previously been shown theoretically that strain applied in the plane of (110) or (111) oriented quantum wells can act to cancel the spin-orbit field from bulk inversion asymmetry. In this thesis, we study the effect on the spin dynamics of of strain applied to a (110) quantum well and also investigate a (111) sample for its suitability in such experiments.