Dresden 2014 – scientific programme
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MA: Fachverband Magnetismus
MA 5: Topological insulators: mostly structure and electronic structure (with HL/O/TT)
MA 5.4: Talk
Monday, March 31, 2014, 10:15–10:30, POT 051
Surface-Dominated Transport on a Bulk Topological Insulator — •Lisa Kühnemund1, Lucas Barreto2, Frederik Edler1, Christoph Tegenkamp1, Jianli Mi3, Martin Bremholm3, Bo Brummerstedt Iversen3, Christian Frydendahl2, Marco Bianchi2, and Philip Hofmann2 — 1Leibniz Universität Hannover, Inst. f. Festkörperphysik — 2Aarhus University, Dep. of Physics and Astronomy, iNANO — 3Aarhus University, Center for Materials Crystallography, iNANO
Topological insulators are guaranteed to support metallic surface states on an insulating bulk, and one should thus expect that the electronic transport in these materials is dominated by the surfaces states. Alas, due to the high remaining bulk conductivity, surface contributions to transport have so-far only been singled out indirectly via quantum oscillations, or for devices based on gated and doped topological insulator thin films, a situation in which the surface carrier mobility could be limited by defect and interface scattering. Here we present a direct measurement of surface-dominated conduction on an atomically clean surface of Bi2Te2Se. Using nano-scale four point setups with variable contact distance, we show that the transport at 30 K is two-dimensional rather than three-dimensional and by combining these measurements with angle-resolved photoemission results from the same crystals, we find a surface state mobility of 390(30) cm2V−1s−1 at 30 K at a carrier concentration of 8.71(7)× 1012 cm−2.