# Microscopic theory for the light-induced anomalous Hall effect in graphene

## TL;DR

This paper models the light-induced anomalous Hall effect in graphene using a quantum Liouville approach, revealing different mechanisms in weak and strong laser fields and linking them to Floquet band topology.

## Contribution

It introduces a comprehensive quantum model explaining the anomalous Hall effect in graphene under ultrafast light, highlighting the role of Floquet-Bloch bands and population imbalances.

## Key findings

- Hall effect from asymmetric photocarrier populations in weak fields
- Steady state driven by topologically non-trivial Floquet bands in strong fields
- Potential for designing ultrafast quantum devices with Floquet engineering

## Abstract

We employ a quantum Liouville equation with relaxation to model the recently observed anomalous Hall effect in graphene irradiated by an ultrafast pulse of circularly polarized light. In the weak-field regime, we demonstrate that the Hall effect originates from an asymmetric population of photocarriers in the Dirac bands. By contrast, in the strong-field regime, the system is driven into a non-equilibrium steady state that is well-described by topologically non-trivial Floquet-Bloch bands. Here, the anomalous Hall current originates from the combination of a population imbalance in these dressed bands together with a smaller anomalous velocity contribution arising from their Berry curvature. This robust and general finding enables the simulation of electrical transport from light-induced Floquet-Bloch bands in an experimentally relevant parameter regime and creates a pathway to designing ultrafast quantum devices with Floquet-engineered transport properties.