Effects of the Spin-Orbit Interaction on Transport and Optical Properties of III-V Semiconductor Quantum Wells

Detta är en avhandling från Division of Solid State Theory, Department of Physics, University of Lund, Sölvegatan 14A, SE-223 62 Lund

Sammanfattning: Effects of the intrinsic electron spin-orbit interaction on transport and optical properties of III-V semiconductor quantum wells have been studied theoretically. It is shown that due to crystal anisotropy of this interaction, the weak localization magnetoresistance in a magnetic field parallel to interfaces is very sensitive to the epitaxy growth direction and also to the orientation of the magnetic field with respect to the crystal axes. Spin-orbit effects on the resonant Raman scattering from intrasubband electronic excitations have been investigated. We demonstrate that the spin-orbit interaction leads to the so-called "spin-spin" and "spin-charge" quantum interference of Raman amplitudes. The interference manifests itself in an asymmetry of the spin-flip and non-spin-flip Raman spectra with respect to the directions of circular polarizations of the incident and the scattered photons. In the case of resonance with a heavy-hole subband, the polarization asymmetry of the spin-flip spectrum can be detected only if the heavy and light-hole subbands are hybridized. Experimental conditions and selection rules for observation of the spin-charge interference have been analysed. Finally, we have studied the spatial and temporal evolution of an inhomogeneous spin distribution created by a focused laser pulse in a magnetic field applied parallel to a quantum well. Instead of the conventional exponential relaxation typical of a homogeneous spin distribution, we have found that the shape of the spin packet oscillates in time and space, as a result of the interplay between the spin-orbit interaction and the magnetic field. The amplitude of the oscillations depends on the direction, as well as on the strength of the magnetic field.

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