Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 52: Topological Insulators II (joined session with TT)
MA 52.3: Vortrag
Donnerstag, 23. März 2017, 15:15–15:30, POT 251
Tuning Quantum Transport and Interference in Topological Nanowires — •Vincent Sacksteder1 and Quansheng Wu2 — 1W155 Wilson Building, Royal Holloway University of London, Egham Hill, Egham, TW20 0EX, United Kingdom — 2Theoretical Physics and Station Q Zurich, ETH Zurich, 8093 Zurich, Switzerland
We study the magnetoconductance of topological insulator nanowires in a longitudinal magnetic field, including Aharonov-Bohm, Altshuler-Aronov-Spivak, perfectly conducting channel, and universal conductance fluctuation effects. We show that changing the Fermi energy can tune a wire from from ballistic to diffusive conduction and to localization. In both ballistic and diffusive single wires we find both Aharonov-Bohm and Altshuler-Aronov-Spivak oscillations with similar strengths, accompanied by quite strong universal conductance fluctuations (UCFs), all with amplitudes between 0.3 and 1 conductance quanta. This contrasts strongly with the average behavior of many wires, which shows Aharonov-Bohm oscillations in the ballistic regime and Altshuler-Aronov-Spivak oscillations in the diffusive regime, with both oscillations substantially larger than the conductance fluctuations. We also show that in long wires the perfectly conducting channel is visible at a wide range of energies within the bulk gap. We present typical conductance profiles at several wire lengths, showing that conductance fluctuations can dominate the average signal. Similar behavior will be found in carbon nanotubes.