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HL: Fachverband Halbleiterphysik
HL 37: Transport: Topological insulators 3 (TT with HL/DS)
HL 37.3: Vortrag
Dienstag, 17. März 2015, 14:30–14:45, H 0110
Effects of random Rashba spin-orbit coupling and magnetic impurities on edge state transport in topological insulators — Lukas Kimme1, •Bernd Rosenow1, and Arne Brataas2 — 1Institut für Theoretische Physik, Universität Leipzig, D-04103, Leipzig, Germany — 2Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
CdTe/HgTe quantum-wells that exceed a critical thickness host topologically protected edge states, which give rise to a quantized conductance. Despite the topolgical protection, experimentally a mean free path of a few microns is found [1]. The experimentally observed weak temperature dependence of the mean free path challenges proposed theoretical explanations, many of which predict power law behaviors. We here consider a model where edge electrons experience spatially random Rashba spin-orbit coupling, and are also coupled to a magnetic impurity. Using a rate equation model, we determine the steady state of the impurity spin in the finite bias regime, and compute both linear and nonlinear resistances. For a finite density of impurity spins, we obtain a weak temperature dependence of the mean free path, in agreement with experimental findings.
[1] M. König, S. Wiedmann, C. Brüne, A. Roth, H. Buhmann,
L. W. Molenkamp, X.-L. Qi, and S.-C. Zhang,
Science 318, 766 (2007).