Quantized nonlinear Hall effect from chiral monopole

TL;DR

This paper predicts that in chiral Weyl semimetals, the nonlinear Hall effect can be quantized due to monopole charges, offering a new way to detect chiral asymmetry through transport and optical measurements.

Contribution

It introduces a theory showing nonlinear Hall effect quantization in chiral Weyl semimetals, linking it to monopole charges and relaxation asymmetries, extending previous understanding.

Findings

Nonlinear Hall effect can be quantized in chiral Weyl semimetals.

Quantization is determined by monopole charge and relaxation times.

Chiral asymmetry can be detected via nonlinear circular dichroism.

Abstract

Nonlinear Hall effect arises in materials without inversion symmetry, and the intrinsic contribution is typically from Berry curvature dipole of non-universal Fermi pockets. Here we propose that nonlinear Hall effect can reach quantization in chiral Weyl semimetals without mirror symmetries. The energy shift between a pair of Weyl nodes leads to chirally asymmetric intra-node relaxation, and the net trace of nonlinear Hall conductivity is thus quantized in units of $e^3/\hbar^2$ and determined by sum of monopole charge weighted by the transport relaxation time. Our theory also applies to mirror symmetric Weyl/Dirac semimetals with chiral anomaly. Additionally, besides DC transport probes, we anticipate that nonlinear circular dichroism measurements could detect chiral asymmetry-induced currents.