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O: Fachverband Oberflächenphysik

O 13: Electronic Structure of Surfaces II

O 13.2: Vortrag

Montag, 16. März 2015, 15:30–15:45, MA 041

Strongly anisotropic spin-orbit splitting in a 2-dimensional electron gas — •Matteo Michiardi¹, Marco Bianchi¹, Maciej Dendzik¹, Jill Miwa¹, Moritz Hoesch², Timur K. Kim², Peter Matzen¹, JianLi Mi³, Martin Bremholm³, Bo Brummerstedt Iversen³, and Philip Hofmann¹ — ¹Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark — ²Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom — ³Center for Materials Crystallography, Department of Chemistry, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark

Near-surface two-dimensional electron gases (2DEG) 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 can be found in the ΓM direction while the states are hardly split along ΓK. We show that this strong anisotropy can be explained by expanding the k · p hamiltonian for 2DEGs to include the possibility of band structure anisotropy as well as both isotropic and anisotropic third order Rashba splitting. 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.