Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 18: Topological Insulators
TT 18.6: Vortrag
Mittwoch, 7. September 2022, 10:45–11:00, H23
Dynamic impurities in two-dimensional topological insulator edge states — •Simon Wozny1, Martin Leijnse1, and Sigurdur I. Erlingsson2 — 1Division of Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund, Sweden — 2School of Science and Engineer- ing, Reykjavik University, Menntavegi 1, IS-101 Reykjavik, Iceland
Two-dimensional topological insulators host one-dimensional helical states at the edges. These are characterized by spin-momentum locking and time-reversal symmetry protects the states from backscattering by potential impurities. Magnetic impurities break time-reversal symmetry and allow for backscattering.
We have investigated the effects of random, aligned but harmonically rotating magnetic impurities. Using the time dependent Green's function (GF) for the system we calculate the time-averaged density of states (DOS) and extract the transmission via a Floquet scattering formalism. For slow driving the DOS and transmission match an average over static impurity orientations, whereas fast driving results in a flat low-energy DOS and transmission with resonances at higher energies related to Floquet sub-band crossings. Resonant driving leads to a nontrivial DOS and transmission. We also investigate the dependence on the ratio between potential and magnetic strength of the impurities.