Electron spin decoherence in diluted magnetic quantum wells

Abstract

We study electron spin dynamics in diluted magnetic quantum wells. The electrons are coupled by exchange interaction with randomly distributed magnetic ions polarized by magnetic field. This coupling leads to both spin relaxation and spin decoherence. We demonstrate that even very small spatial fluctuations of quantum well width dramatically increase rate of decoherence. Depending on the strength of exchange interaction and the amplitude of the fluctuations the decoherence can be homogeneous or inhomogeneous. In the homogeneous regime, the transverse (with respect to magnetic field) component of the electron spin decays on the short time scale exponentialy, while the long-time spin dynamics is non-exponential demonstrating long-lived power law tail. In the inhomogeneous case, the transverse spin component decays exponentially with the exponent quadratic in time

Electric field dependence of the spin relaxation anisotropy in (111) GaAs/AlGaAs quantum wells

“…Interestingly, this simple phenomenological modification better reproduces the anisotropies and the electric field value at the isotropic point. We ascribe the observed discrepancies to the limitation of the model in which only a simple scattering model is taken into account and other spin relaxation processes are not considered such as the QW width and electric field fluctuations which could induce, respectively, spin relaxation through the spatial variation of the confinement energy [27] and produce an inhomogeneous Rashba contribution [28,29]. Moreover, we have neglected the small piezoelectric field present at V = 0 due to the slight lattice mismatch between GaAs and Al 0.3 Ga 0.7 As.…”