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

DOI: 10.1103/PhysRevB.91.035445 DOI Help

Authors: Matteo Michiardi (Aarhus University) , Marco Bianchi (Aarhus University) , Maciej Dendzik (Aarhus University, Denmark) , Jill Miwa (Aarhus University) , Moritz Hoesch (Diamond Light Source) , Timur Kim (Diamond Light Source) , Peter Matzen (Aarhus University) , Jianli Mi (Aarhus University) , Martin Bremholm (Aarhus University) , Bo Brummerstedt Iversen (Aarhus University) , Philip Hofmann (Aarhus University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 91 (3) , PAGES 27702-27707

State: Published (Approved)
Published: January 2015
Diamond Proposal Number(s): 9520

Abstract: Near-surface two-dimensional electron gases on the topological insulator Bi2Te2Se 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 (approximately 0.06 A-1) can be found in the ¯  ¯ M direction while the states are hardly split along ¯  ¯ K. The direction of the anisotropy is found to be qualitatively inconsistent with results expected for a third-order anisotropic Rashba Hamiltonian. However, a k · 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 tunable doping offers the opportunity to engineer not only the size of the spin-orbit splitting but also its direction.

Subject Areas: Physics


Instruments: I05-ARPES

Other Facilities: ASTRID