Disordered Parity Anomalous Semimetal

TL;DR

This paper explores how disorder can induce a topological phase transition in magnetic topological insulators, leading to a parity anomalous semimetal with a half-quantized Hall conductance and the emergence of a gapless Dirac fermion.

Contribution

It demonstrates that strong disorder can transform trivial insulators into parity anomalous semimetals and diffusive metals, revealing new disorder-driven topological phases in magnetic topological insulators.

Findings

Disorder induces a transition from parity anomalous semimetal to diffusive metal.

Strong disorder can create a topological phase in trivial insulators.

A gapless Dirac fermion emerges with increasing disorder strength.

Abstract

The parity anomalous semimetal is a topological state of matter characterized by its semi-metallic nature and a quantum Hall conductance of one-half $e^{2}/h$ ($e$ is the elementary charge and $h$ is the Planck constant). Here we investigate the topological phase transition driven by disorder in a semi-magnetic structure of topological insulator, and narrow-gap weak topological insulator film. We demonstrate that strong disorder not only leads to a topological transition from the parity anomalous semimetal to a diffusive metal with non-quantized anomalous Hall conductance, but also induces the topological phase in a trivial insulating phase. Our calculations of the local density of states provide clear picture for the formation of a single gapless Dirac fermion, which emerges as the disorder strength increases. The half quantized Hall effect is attributed to the existence of the gapless Dirac cone. Our findings of disorder-induced parity anomalous semimetal and diffusive metal significantly advance our understanding of the disorder-driven topological phase transition in magnetic topological insulators, opening up new avenues for further exploration in the field of quantum materials.