Effect of disorder on 2D topological merging transition from a Dirac semi-metal to a normal insulator
CNRS UMR5672 - Laboratoire de Physique de l'Ecole Normale Supérieure de Lyon 46, Allée d'Italie, 69007 Lyon, France, EU
Received: 19 March 2013
Accepted: 10 June 2013
We study the influence of disorder on the topological transition from a two-dimensional Dirac semi-metal to an insulating state. This transition is described as a continuous merging of two Dirac points leading to a semi-Dirac spectrum at the critical point. The latter is characterized by a dispersion relation linear in one direction and quadratic in the orthogonal one. Using the self-consistent Born approximation and renormalization group we calculate the density of states above, below and in the vicinity of the transition in the presence of different types of disorder. Beyond the expected disorder smearing of the transition we find an intermediate disordered semi-Dirac phase. On one side this phase is separated from the insulating state by a continuous transition while on the other side it evolves through a crossover to the disordered Dirac phase.
PACS: 73.20.At – Surface states, band structure, electron density of states / 73.20.Hb – Impurity and defect levels; energy states of adsorbed species / 73.43.Nq – Quantum phase transitions
© EPLA, 2013