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

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 ($\alpha$) and the Dresselhaus (${\beta }_3$) 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.

arXiv comment5 pages, 4 figures, journal submission

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• Imprinting spatial helicity structure of vector vortex beam on spin texture in semiconductors
• Spin helices in GaAs quantum wells: Interplay of electron density, spin diffusion, and spin lifetime
• Direct imprinting of arbitrary spin textures using programmable structured light in a semiconductor two-dimensional electron gas
• Faraday and Kerr rotation due to photoinduced orbital magnetization in two-dimensional electron gas