Robust band of critical states in time-reversal symmetry-broken fermionic systems with lattice selective disorder

Eduardo V Castro,M Pilar López-Sancho,María A H Vozmediano,Raphael De Gail

doi:10.1103/physrevresearch.1.033129

Abstract

We analyze the localization properties of two dimensional systems based on partite lattices with a basis. Contrary to standard results, we find that a band of critical states emerges for systems in the unitary class A preserving spin symmetry when disorder is unevenly distributed over the basis atoms. The critical metal arises when the less disordered sublattice is connected and has time reversal symmetry broken. The unexpected robustness to disorder presented here is an appealing result which can be measured in optical lattices.

Highlights

Anderson localization [1] is one of the best studied phenomena in modern condensed matter
All the models discussed in this work, except the TI model on the honeycomb lattice, are examples of Chern insulators defined on partite two-dimensional lattices
The objective was to discuss the generality and robustness of the band of critical states found in the Haldane model under strong selective disorder [16]

Summary

INTRODUCTION

Anderson localization [1] is one of the best studied phenomena in modern condensed matter. It was established numerically that at the center of each Landau level band there is only one critical state, an extended state where the localization length diverges linearly with system size, indicative of a vanishing β scaling function [4,5]. The case when both timereversal symmetry T and spin-rotation symmetry are broken has been the subject of recent investigation [6,7,8,9], and the physics was found to be different. For selective disorder we have disorder strength Wi for sublattice i

MODELS AND RESULTS

Published by the American Physical Society

DOS level spacing variance

The Hamiltonian in both cases can be written as

DISCUSSION AND SUMMARY