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arXiv · 1803.10644

Persistent Spin Helix Manipulation by Optical Doping of a CdTe Quantum Well

F. Passmann·S. Anghel·T. Tischler·A. V. Poshakinskiy·S. A. Tarasenko·G. Karczewski·T. Wojtowicz·A. D. Bristow·M. Betz
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Abstract

Time-resolved Kerr-rotation microscopy explores the influence of optical doping on the persistent spin helix in a [001]-grown CdTe quantum well at cryogenic temperatures. Electron spin diffusion dynamics reveal a momentum-dependent effective magnetic field providing SU(2) spin-rotation symmetry, consistent with kinetic theory. The Dresselhaus and Rashba spin-orbit coupling parameters are extracted independently from rotating the spin helix with external magnetic fields applied parallel and perpendicular to the effective magnetic field. Most importantly, a non-uniform spatiotemporal precession pattern is observed. The kinetic theory framework of spin diffusion allows for modeling of this finding by incorporating the photocarrier density into the Rashba ($α$) and the Dresselhaus ($β_3$) parameters. Corresponding calculations are further validated by an excitation-density dependent measurement. This work shows universality of the persistent spin helix by its observation in a II-VI compound and the ability to fine-tune it by optical doping.

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F. Passmann, S. Anghel, T. Tischler, A. V. Poshakinskiy, S. A. Tarasenko, G. Karczewski, T. Wojtowicz, A. D. Bristow, M. Betz. 2018-03-28. Persistent Spin Helix Manipulation by Optical Doping of a CdTe Quantum Well. https://doi.org/10.1103/physrevb.97.201413

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