Robustness of Half-Integer Quantized Hall Conductivity against Disorder in an Anisotropic Dirac Semimetal with Parity Anomaly

TL;DR

This paper proposes an anisotropic Dirac semimetal model that maintains nearly half-integer quantized Hall conductivity despite disorder, providing a robust platform to study the parity anomaly in topological semimetals.

Contribution

It introduces a new anisotropic Dirac semimetal model with broken time-reversal symmetry that exhibits stable half-integer Hall conductivity under disorder.

Findings

Disorder effects are strongly suppressed in the model.

Nearly half-integer quantization persists over a wide disorder range.

The model can be realized on a deformed honeycomb lattice with magnetic flux.

Abstract

Two-dimensional Dirac semimetals with a single massless Dirac cone exhibit the parity anomaly. Usually, such a kind of anomalous topological semimetallic phase in real materials is unstable where any amount of disorder can drive it into a diffusive metal and destroy the half-integer quantized Hall conductivity as an indicator of parity anomaly. Here, based on low-energy effective model, we propose an anisotropic Dirac semimetal which explicitly breaks time-reversal symmetry and carries a half-integer quantized Hall conductivity. This topological semimetallic phase can be realized on a deformed honeycomb lattice subjected to a magnetic flux. Moreover, we perceptively investigate the disorder correction to the Hall conductivity. The results show that the effects of disorder can be strongly suppressed and thereby the nearly half-integer quantization of Hall conductivity can exist in a wide region of disorder, indicating that our proposed anisotropic Dirac semimetal is an exciting platform to investigate the parity anomaly phenomena.