Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: HL Poster I

HL 12.26: Poster

Montag, 1. April 2019, 17:30–20:00, Poster E

Phase-coherent transport and gating of top-down etched bulk-insulating topological insulator nanowires — •Dingxun Fan, Matthias Rössler, Oliver Breunig, Andrea Bliesener, Gertjan Lippertz, Alexey Taskin, and Yoichi Ando — II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany

A solid understanding of the phase-coherent transport properties of the surface states in quantum devices based on topological insulator (TI) nanowires is of fundamental importance for the exploration of various applicational concepts, e.g. Majorana-fermion-based topological quantum computing and spintronic devices. In general, a TI nanowire can be realized by natural growth, mechanical exfoliation or top-down etching from thin films. Despite the significant progress that has been achieved in the magnetotransport properties of the first two cases, which highlights the topological nature of quantized surface states, the investigation of thin-film-based nanowire devices is far from complete in revealing the role of topological surface states in transport.

Here we study the transport properties of top-gated (Bi_1−xSb_x)₂Te₃ nanowires with width down to 100 nm realized by etching MBE-grown bulk-insulating thin films. Low temperature transport measurements show full gate tunability of both top and bottom surfaces. Mesoscopic transport phenomena including weak anti-localization, universal conductance fluctuations and Aharonov-Bohm oscillations are measured and compared both at and away from the Dirac point. The effect of local gating is also discussed.