title: Theory of the topological anderson insulator.
abstract: 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 sigma(z) 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.
authors.affiliation: Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands.
authors.forename: C W
authors.initials: CW
authors.lastname: Groth
authors.forename: M
authors.initials: M
authors.lastname: Wimmer
authors.forename: A R
authors.initials: AR
authors.lastname: Akhmerov
authors.forename: J
authors.initials: J
authors.lastname: Tworzydło
authors.forename: C W J
authors.initials: CW
authors.lastname: Beenakker