Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 29: TR: Nanoelectronics I: Quantum Dots, Wires, Point Contacts 1
TT 29.13: Vortrag
Donnerstag, 25. März 2010, 12:45–13:00, H19
Theory of the Topological Anderson Insulator — •Michael Wimmer1, Christoph W. Groth1, Anton R. Akhmerov1, Jakub Tworzydło2, and Carlo W. J. Beenakker1 — 1Instituut-Lorentz, Universiteit Leiden, The Netherlands — 2Institute of Theoretical Physics, Warsaw university, Poland
We present an effective medium theory that explains the disorder-induced transition into a phase of quantized conductance, discovered in computer simulations of HgTe quantum wells [1,2]. It is the combination of a random potential and quadratic corrections ∝ p2σz to the Dirac Hamiltonian that can drive an ordinary band insulator into a topological insulator (having an inverted band gap). We calculate the location of the phase boundary at weak disorder and show that it corresponds to the crossing of a band edge rather than a mobility edge. Our mechanism for the formation of a topological Anderson insulator is generic, and would apply as well to three-dimensional semiconductors with strong spin-orbit coupling.
[1] J. Li et al. Phys. Rev. Lett. 102, 136806 (2009).
[2] H. Jiang et al. Phys. Rev. B 80, 165316 (2009)