Effect of disorder on 2D topological merging transition from a Dirac semi-metal to a normal insulator

Abstract

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.

6 pages, 5 figures

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• Interplay of Coulomb interaction and disorder in a two-dimensional semi-Dirac fermion system
• Tuning Dirac nodes with correlated d-electrons in BaCo_{1-x}Ni_{x}S_{2}
• Weyl semimetallic phase in an interacting lattice system
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• Dynamical manipulation of Dirac points in the Kitaev honeycomb model
• Unconventional scaling theory in disorder-driven quantum phase transition
• Robust semi-Dirac points and unconventional topological phase transitions in doped superconducting Sr2IrO4 tunnel coupled to t2g electron systems
• Fate of superconductivity in disordered Dirac and semi-Dirac semimetals
• Dirac points merging and wandering in a model Chern insulator