Correlated disorder induced anomalous transport in magnetically doped topological insulators

TL;DR

This study investigates how correlated non-magnetic disorder affects transport in magnetically doped topological insulator thin films, revealing various topological phases and transitions influenced by disorder orientation.

Contribution

It demonstrates the emergence of different topological Anderson insulator phases under correlated disorder and analyzes their stability and transitions using a self-consistent Born approximation.

Findings

Quantized transport persists for diagonal quasi-periodicity.

Multiple topological phases, including QAHI, QSCI, and QSHI, are realized before Anderson localization.

Topological phase transitions depend on disorder orientation and strength.

Abstract

We examine the transport properties of magnetically doped topological insulator (TI) thin films subject to correlated non-magnetic disorder. For the disorder we choose a quasi-periodic potential with a random phase. We restrict the disorder to a central region, which is coupled to two leads in a clean quantum spin Hall insulator (QSHI) state and concentrate on different orientations of the quasi-periodicity in the two-dimensional central region. In the case of a diagonally oriented or purely longitudinal quasi-periodicity we find different topological Anderson insulator (TAI) phases, with a quantum anomalous Hall insulator (QAHI), a quantum spin Chern insulator (QSCI), or a QSHI phase being realized before the Anderson insulation takes over at large disorder strength. Quantized transport from extended bulk states is found for diagonal quasi-periodicity in addition to the above TAI phases that are also observed for the case of uncorrelated disorder. For a purely transverse orientation of the quasi-periodicity the emerging QSHI and QSCI phases persist to arbitrarily strong disorder potential. These topological phase transitions (except to the Anderson insulator phase), can be understood from a self consistent Born approximation.