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HL: Fachverband Halbleiterphysik
HL 70: Spin phenomena in semiconductors
HL 70.3: Vortrag
Donnerstag, 19. März 2020, 15:30–15:45, POT 251
Spatial and temporal evolution of electron spins in [110] grown GaAs quantum wells — •Karl Schiller, Sergiu Anghel, and Markus Betz — Experimentelle Physik 2, Technische Universität Dortmund, Otto-Hahn-Straße 4a, 44227 Dortmund, Germany
Spin-orbit interaction (SOI) is a key mechanism in manipulating electron spins in non-centrosymmetric semiconductor heterostructures and can be understood in terms of an effective magnetic field Beff acting on the moving electrons. At the same time, the SOI can serve as a source of dephasing (D’yakonov-Perel mechanism), as the precession frequency becomes dependent on the electron trajectory. However, this mechanism is suppressed in [110] quantum wells (QWs) for spins aligned along the same direction as the Beff and, consequently, long spin lifetimes can be achieved [1].
We have investigated spatial and temporal evolution of optically injected spin distributions for QWs with different thicknesses. For that, we have used non-degenerate and time-resolved magneto-optic Kerr rotation microscopy. The output of a mode-locked Ti:Sapphire oscillator is split into circularly polarized pump pulse at 1.57 eV, which excites a spin distribution, and linear polarized probe pulse to detect it, with its energy depending on the QW thickness. We have observed pronounced anisotropic spin diffusion between the [001] and [110] directions for QW thicknesses of 20 nm, 14 nm and 9.6 nm.
[1] Y. Ohno et al., Phys. Rev. Lett. 83, 4196 (1999)