Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 32: Transport Properties I (mainly Spin Physics and Magnetic Fields)
HL 32.6: Vortrag
Dienstag, 27. März 2012, 11:30–11:45, EW 203
Strain and Electric Field Control of the Spin-Dynamics in GaAs/AlGaAs Quantum Wells — •David English1, Peter Eldridge3, Jens Hübner1, Richard Harley2, and Michael Oestreich1 — 1Institute for Solid State Physics, Leibniz University Hannover, Appelstr. 2, 30167 Hannover, Germany — 2School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK — 3Foundation for Research and Technology, IESL, PO Box 1527, 71110, Heraklion, Crete, Greece
We measure by spin quantum beat spectroscopy the anisotropy of the electron Landé g-factor and the spin relaxation rate, Γs, in (001) AlGaAs/GaAs quantum wells. The anisotropy is either induced by an applied electric field, applied strain or an asymmetrically grown quantum well. The anisotropy of g and Γs are produced by different microscopic mechanisms. In general an anisotropic g-factor implies an asymmetric conduction electron wavefunction, whereas the anisotropic spin relaxation rate requires a non-zero expectation value of the valence band potential gradient on the conduction band states. Therefore, a comparison of the two in-plane anisotropies provides insight into the effects on the band edges induced by the different perturbations.
We find that an electric field generates anisotropy of both g and Γs. However, it is shown that an asymmetric potential produces anisotropy in g but not Γs while the opposite occurs for strain which induces an in-plane anisotropy of Γs but leaves the g-factor isotropic. Therefore, we unambiguously reveal the different microscopic mechanisms of the three perturbations.