Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 91: Focus Session: Frontiers of Electronic Structure Theory - Non-Equilibrium Phenomena at the Nano-Scale VI (organized by O)
TT 91.1: Topical Talk
Thursday, April 3, 2014, 10:30–11:00, TRE Ma
Localization at the edge of 2D topological insulator by Kondo impurities — •Boris Altshuler1, Igor Aleiner1, and Vladimir Yudson2 — 1Physics Department, Columbia University, New York, NY 10027, USA — 2Institute for Spectroscopy, Russian Academy of Sciences,Troitsk, Moscow 142190, Russia
Recent interest to the topological insulators [1] is inspired by the fact that their boundaries host gapless electronic excitations, which are extended and make the system conductive even in the presence of a potential disorder. 1D edge of a 2D topological insulator is predicted to have perfect conductance (2e2/h): right and left moving electrons carry opposite spins and potential disorder cannot flip spins and thus causes neither back-scattering nor the usual 1D localization.
What if there are localized spins coupled to the edge electrons? It turns out that the conductivity is still perfect provided that this coupling conserves the z-projection of the total spin of the impurities and electrons. Magnetic anisotropy violates this conservation and causes the backscattering even at T=0, i.e. an arbitrary small density of the spins with arbitrary weak anisotropy of the coupling leads to Anderson localization of the edge states in long enough samples [3]. The conclusion follows from the mapping of the electron-spin coupling to the well-studied problem [2] of disordered Luttinger liquid.
1. M.Z. Hasan and C.L. Kane, Rev. Mod. Phys. 82, 3045 (2010).
2. T.Giamarchi and H.J.Schulz, Phys. Rev. B 37, 325 (1988).
3. B.L.Altshuler, I.L.Aleiner, V.I. Yudson Phys. Rev. Lett
111, 086401 (2013)