Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 32: Spintronics
HL 32.3: Vortrag
Mittwoch, 3. April 2019, 15:30–15:45, H33
Acoustic spin transport in planar GaAs quantum wires — •Paul L. J. Helgers1,2, Klaus Biermann1, Haruki Sanada2, Yoji Kunihashi2, and Paulo V. Santos1 — 1Paul-Drude Institut, Leibniz-Institut im Forschungsverbund Berlin e.V., Germany — 2NTT Basic Research Laboratories, NTT Corporation, Atsugi, Japan
We investigate a concept for single-photon sources, based on planar GaAs quantum wires (QWR). The QWRs form during anisotropic overgrowth of a 10 nm quantum well (QW) on pre-patterned GaAs(001) substrates by molecular beam epitaxy. The fabrication process results in potential fluctuations along the QWR axis due to line-edge-roughness (LER). LER potentially leads to Elliot-Yafet spin relaxation. We measure LER to be small as compared to the QWR width and expect it to play only a minor role during spin transport.
We study charge transport in the QWRs by a surface acoustic wave (SAW) over tens of microns. Moreover, we detect SAW-assisted carrier transfer between the QWR and the surrounding QW, which is otherwise prevented by a potential barrier. The one-dimensionality of the QWR reduces Dyakonov-Perel (DP) spin dephasing, leading to enhanced spin lifetimes with respect to the QW. We observe acoustic spin transport up to at least 15 micron. During transport, the spins rotate around the Dresselhaus field with a precession length corresponding to the calculated one for these QWRs, proving that the spin transport takes place in the QWRs rather than in the surrounding QW.