Transport Theory of Half-quantized Hall Conductance in a Semi-magnetic Topological Insulator

TL;DR

This paper explains the microscopic transport mechanism behind the experimentally observed half-quantized Hall conductance in semi-magnetic topological insulators, highlighting the role of dephasing and edge chiral currents.

Contribution

It reveals how half-quantized Hall conductance persists in metallic regimes due to edge chiral currents under strong dephasing, providing a microscopic understanding.

Findings

Half-quantized Hall conductance remains stable with increasing dephasing.

Longitudinal conductance varies with Fermi energy and dephasing strength.

Results align with experimental temperature-dependent conductance measurements.

Abstract

Recently,a half-quantized Hall conductance (HQHC) plateau is experimentally observed in a semi-magnetic topological insulator heterostructure. However,the heterostructure is metallic with a nonzero longitudinal conductance, which contradicts the common belief that quantized Hall conductance is usually observed in insulators.In this work,we systematically study the surface transport of the semi-magnetic topological insulator with both gapped and gapless Dirac surfaces in the presence of dephasing process.In particular, we reveal that the HQHC is directly related to the half-quantized chiral current along the edge of a strongly dephasing metal. The Hall conductance keeps a half-quantized value for large dephasing strengths, while the longitudinal conductance varies with Fermi energies and dephasing strengths. Furthermore, we evaluate both the conductance and resistance as a function of the temperature, which is consistent with the experimental results.Our results not only provide the microscopic transport mechanism of the HQHC,but also are instructive for the probe of the HQHC in future experiments.