Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 13: Topological Insulators: Mostly Structure and Electronic Structure (organized by HL)

TT 13.4: Vortrag

Montag, 31. März 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.