Spin polarization, dephasing and photoinduced spin diffusion in (110)-grown two-dimensional electron systems

Abstract

We study the optically induced spin polarization, spin dephasing and diffusion in several high-mobility two-dimensional electron systems, which are embedded in GaAs quantum wells grown on (110)-oriented substrates. The experimental techniques comprise a two-beam magneto-optical spectroscopy system and polarization-resolved photoluminescence. Under weak excitation conditions at liquid-helium temperatures, we observe spin lifetimes above 100 ns in one of our samples, which are reduced with increasing excitation density due to additional, hole-mediated, spin dephasing. The spin dynamic is strongly influenced by the carrier density and the ionization of remote donors, which can be controlled by temperature and above-barrier illumination. The absolute value of the average electron spin polarization in the samples is directly observable in the circular polarization of photoluminescence collected under circularly polarized excitation and reaches values of about 5 percent. Spin diffusion is studied by varying the distance between pump and probe beams in micro-spectroscopy experiments. We observe diffusion lengths above 100 $\mu$m and, at high excitation intensity, a nonmonotonic dependence of the spin polarization on the pump-probe distance.

10 pages, 6 figures

References in corpus (6)

• Spin noise spectroscopy in GaAs (110) quantum wells: Access to intrinsic spin lifetimes and equilibrium electron dynamics
• Spin coherence of holes in GaAs/AlGaAs quantum wells
• Spin-orbit fields in asymmetric (001) quantum wells
• Spin relaxation due to the Bir-Aronov-Pikus mechanism in intrinsic and $p$-type GaAs quantum wells from a fully microscopic approach
• Pure spin photocurrents
• Spin dephasing and photoinduced spin diffusion in high-mobility 110-grown GaAs-AlGaAs two-dimensional electron systems

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• Weak localization in low-symmetry quantum wells
• Optical spin orientation of minority holes in a modulation-doped GaAs/(Ga,Al)As quantum well
• Spin currents of exciton polaritons in a microcavity with (110)-oriented quantum well
• Fast optical control of spin in semiconductor interfacial structures
• Impurity states of electrons on the surface of a nanotube in a magnetic field