Deconvolution of Rashba and Dresselhaus spin-orbit coupling by crystal axis dependent measurements of coupled InAs/GaSb quantum wells

Abstract

The Dresselhaus spin orbit interaction is expected to perturb the quantum spin Hall phase predicted to arise within InAs/GaSb coupled quantum wells. As such, to gain a greater understanding of this spin-orbit interaction, the spin orbit coupling in two InAs/GaSb coupled quantum wells, grown along the [001] axis, is investigated along 3 different in-plane crystallographic axes. Due to the crystallographic axis dependence of the Dresselhaus spin orbit coupling, we can deconvolute this coupling from the axis-invariant Rashba spin orbit coupling. We find that the Dresselhaus parameter is robust against an external gate bias and small changes in growth conditions, with an associated Dresselhaus parameter of (0.20±0.07)10-11 eVm being measured across all samples and top gate bias conditions. In addition we show that the asymmetries associated with the coupled quantum well structure, leading to the Rashba spin orbit coupling, are likely to play a dominant role in determining the spin orbit interaction experienced by a quantum spin Hall state as the system is tuned towards charge neutrality.

Magnetotransport Signatures of Superconducting Cooper Pairs Carried by Topological Surface States in Bismuth Selenide

“…42 We also note that there are apparent deviations from the cos 2 θ dependence (Figure 3), which could reflect the presence of Rashba and Dresselhaus terms in Hamiltonian, with different relative strengths; although we leave this study for future investigations, it is likely that more involved fitting of AMR data can lead to a deeper understanding of the additional Hamiltonian terms. 43,44 Although the WAL measurements and AMR as a function of θ did not reveal notable and specific manifestations of Cooper pairs carried by TSS, our MR hysteresis and AMR switching (Figure 1) are very robust and we expect them to be highly reproducible by other researchers. We have tested a significant number of samples with variations in dimensions, impurity or defect concentrations, and bulk versus surface conductivities, and all exhibited MR hysteresis and AMR switching.…”

“…Not coincidentally, ferromagnetic interactions that keep the spin of the carriers perpendicular to the current (and aligned with magnetic field) display a very similar AMR as a function of field orientation, well-known for spin–orbit coupled systems . We also note that there are apparent deviations from the cos 2 θ dependence (Figure ), which could reflect the presence of Rashba and Dresselhaus terms in Hamiltonian, with different relative strengths; although we leave this study for future investigations, it is likely that more involved fitting of AMR data can lead to a deeper understanding of the additional Hamiltonian terms. , …”

Anisotropic Kondo screening induced by spin-orbit coupling in quantum wires

“…Since θ SOC is associated with the ratio α /β, its precise determination (e.g. using scanning tunneling spectroscopy) in conjuction with additional measurements [56][57][58] would give access to the absolute values of α and β. Panel (a) in Fig.…”

“…The presence of other features in the curves indicates that a better strategy to find θ SO is by exploiting the expected symmetry around θ SO . In any case, this method of finding the Rashba and Dresselhaus couplings can be used as a complementary technique to other proposed procedures [56][57][58].…”