# Optical absorption in interacting and nonlinear Weyl semimetals

## TL;DR

This paper develops a theoretical framework for optical absorption in three-dimensional Weyl semimetals, revealing how Berry curvature, Coulomb interactions, and spectral nonlinearity induce valley polarization and topologically nontrivial excitons.

## Contribution

It introduces a novel theory combining Berry curvature, Coulomb interactions, and spectral nonlinearity to explain optical phenomena in Weyl semimetals, including valley polarization and topological excitons.

## Key findings

- Berry curvature and interactions enable light-induced valley polarization
- Identification of topologically nontrivial Mahan excitons with vorticity
- Analytical model supports numerical results

## Abstract

It has been recently predicted that the interplay between Coulomb interactions and Berry curvature can produce interesting optical phenomena in topologically nontrivial two-dimensional insulators. Here, we present a theory of the optical absorption for three-dimensional, hole-doped Weyl semimetals. We find that the Berry curvature, Coulomb interactions and the nonlinearity in the single-particle energy spectrum can together enable a light-induced valley polarization. We support and supplement our numerical results with an analytical toy model calculation, which unveils topologically nontrivial Mahan excitons with nonzero vorticity.