2009/08/31 by C. W. Groth, M. Wimmer, A. R. Akhmerov +2 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevlett.103.196805
published as Phys. Rev. Lett. 103, 196805 (2009) · 4 pages, 3 figures (updated figures, calculated DOS)
arxiv created 2009/10/20 · arxiv updated 2013/07/09
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. It is the combination of a random potential and quadratic corrections proportional to p2 sigmaz 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.