Singular Effects of Spin-Flip Scattering on Gapped Dirac Fermions

TL;DR

This paper studies how spin-flip scattering influences the Hall effect and spectral features of gapped Dirac fermions, revealing quantized Hall conductivity jumps and enhanced spectral properties at band edges.

Contribution

It uncovers the singular effects of spin-flip scattering on Hall transport and spectral properties, highlighting the quantized Hall conductivity changes at band edges.

Findings

Hall conductivity exhibits a quantized jump of e^2/2h at band edges.

Spectral properties like density of states are greatly enhanced at band edges.

Berry curvature becomes singular at band edges in the weak scattering regime.

Abstract

We investigate the effects of spin-flip scattering on the Hall transport and spectral properties of gapped Dirac fermions. We find that in the weak scattering regime, the Berry curvature distribution is dramatically compressed in the electronic energy spectrum, becoming singular at band edges. As a result the Hall conductivity has a sudden jump (or drop) of $e^2/2h$ when the Fermi energy sweeps across the band edges, and otherwise is a constant quantized in units of $e^2/2h$. In parallel, spectral properties such as the density of states and spin polarization are also greatly enhanced at band edges. Possible experimental methods to detect these effects are discussed.