Strongly anisotropic spin-orbit splitting in a two-dimensional electron gas

Abstract

Near-surface two-dimensional electron gases on the topological insulator Bi${}_2$Te${}_2$Se are induced by electron doping and studied by angle-resolved photoemission spectroscopy. A pronounced spin-orbit splitting is observed for these states. The $k$-dependent splitting is strongly anisotropic to a degree where a large splitting ($\approx 0.06$ Å${}^{-1}$) can be found in the $\bar{\Gamma }\bar{M}$ direction while the states are hardly split along $\bar{\Gamma }\bar{K}$. The direction of the anisotropy is found to be qualitatively inconsistent with results expected for a third-order anisotropic Rashba Hamiltonian. However, a $\mathbf{k}\cdot \mathbf{p}$ model that includes the possibility of band structure anisotropy as well as both isotropic and anisotropic third order Rashba splitting can explain the results. The isotropic third order contribution to the Rashba Hamiltonian is found to be negative, reducing the energy splitting at high $k$. The interplay of band structure, higher order Rashba effect and tuneable doping offers the opportunity to engineer not only the size of the spin-orbit splitting but also its direction.

arXiv comment5 pages, 4 figures

References in corpus (18)

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Cited by in corpus (9)

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• Spin Hall photoconductance in a 3D topological insulator at room temperature
• Optical manipulation of Rashba-split 2-Dimensional Electron Gas
• Tunable two-dimensional electron gas at the surface of thermoelectric material In${}_4$Se${}_3$
• Optimizing one dimensional superconducting diodes: Interplay of Rashba spin-orbit coupling and magnetic fields
• Electronic Structure of Fe${}_{1.08}$Te bulk crystals and epitaxial FeTe thin films on Bi${}_2$Te${}_3$
• Current-induced spin polarisation in Rashba-Dresselhaus systems under different point groups
• Observation of Dirac Charge Density Waves in Bi${}_2$Te${}_2$Se
• Classification of spin Hall effect in two-dimensional systems