Robustness of half-integer quantized Hall conductivity against disorder in an anisotropic Dirac semimetal with parity anomaly

Two-dimensional Dirac semimetals with a single massless Dirac cone exhibit a 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 a low-energy effective model, we propose an anisotropic Dirac semimetal which explicitly breaks time-reversal symmetry and carries 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.

Automated summary

In this study, we propose an anisotropic Dirac semimetal model which can be realized on a deformed honeycomb lattice subjected to a magnetic flux. The results show that the nearly half-integer quantization of Hall conductivity can exist in a wide region of disorder in this topological semimetallic phase.