Spin-orbit interaction in GaAs wells: From one to two subbands

Abstract

We investigate the Rashba and Dresselhaus spin-orbit (SO) couplings in GaAs quantum wells in the range of well widths $w$ allowing for a transition of the electron occupancy from one to two subbands. By performing a detailed Poisson-Schrödinger self-consistent calculation, we determine all the intra- and inter-subband Rashba (${\alpha }_1$, ${\alpha }_2$, $\eta$) and Dresselhaus (${\beta }_1$, ${\beta }_2$, $\Gamma$) coupling strengths. For relatively narrow wells with only one subband occupied, our results are consistent with the data of Koralek \emph{et al.} [Nature \bfs{48}, 610 (2009)], i.e., the Rashba coupling ${\alpha }_1$ is essentially independent of $w$ in contrast to the decreasing linear Dresselhaus coefficient ${\beta }_1$. When we widen the well so that the second subband can also be populated, we observe that ${\alpha }_2$ decreases and ${\alpha }_1$ increases, both almost linearly with $w$. Interestingly, we find that in the parameter range studied (i.e., very asymmetric wells) ${\alpha }_2$ can attain zero and change its sign, while ${\alpha }_1$ is always positive. In this double-occupancy regime of $w$'s, ${\beta }_1$ is mostly constant and ${\beta }_2$ decreases with $w$ (similarly to ${\beta }_1$ for the single-occupancy regime). On the other hand, the intersubband Rashba coupling strength $\eta$ decreases with $w$ while the intersubband Dresselhaus $\Gamma$ remains almost constant. We also determine the persistent-spin-helix symmetry points, at which the Rashba and the renormalized (due to cubic corrections) linear Dresselhaus couplings in each subband are equal, as a function of the well width and doping asymmetry. Our results should stimulate experiments probing SO couplings in multi-subband wells.

7 pages, 3 figures; minor changes

References in corpus (8)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• An Exact SU(2) Symmetry and Persistent Spin Helix in a Spin-Orbit Coupled System
• Emergence of the persistent spin helix in semiconductor quantum wells
• Direct mapping of the formation of a persistent spin helix: Supplementary information
• Direct determination of spin orbit interaction coefficients and realization of the persistent spin helix symmetry
• Intersubband-induced spin-orbit interaction in quantum wells
• Nonlinear anomalous Hall effect and negative magnetoresistance in a system with random Rashba field

Cited by in corpus (5)

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• Electrical control of spin relaxation anisotropy during drift transport in a two-dimensional electron gas
• Spin drift-diffusion for two-subband quantum wells
• Numerical analysis of the spin-orbit coupling parameters in III-V quantum wells using 8-band Kane model and finite-difference method