# Light-induced anomalous Hall effect in massless Dirac fermion systems and topological insulators with dissipation

## TL;DR

This paper investigates how circularly-polarized laser fields induce a Hall effect in Dirac fermion systems, revealing that external optical driving can dominate intrinsic transport properties and enable ultrafast control.

## Contribution

It introduces a microscopic analysis of light-induced Hall effects in Dirac systems, highlighting the dominance of photocarrier imbalance over intrinsic contributions under strong fields.

## Key findings

- Light-induced Hall effect arises from photocarrier imbalance.
- Floquet-Berry curvature contributes to the effect.
- Strong fields can override intrinsic Hall properties.

## Abstract

Employing the quantum Liouville equation with phenomenological dissipation, we investigate the transport properties of massless and massive Dirac fermion systems that mimics graphene and topological insulators, respectively. The massless Dirac fermion system does not show an intrinsic Hall effect, but it shows a Hall current under the presence of circularly-polarized laser fields as a nature of a optically-driven nonequilibrium state. Based on the microscopic analysis, we find that the light-induced Hall effect mainly originates from the imbalance of photocarrier distribution in momentum space although the emergent Floquet-Berry curvature also has a non-zero contribution. We further compute the Hall transport property of the massive Dirac fermion system with an intrinsic Hall effect in order to investigate the interplay of the intrinsic topological contribution and the extrinsic light-induced population contribution. As a result, we find that the contribution from the photocarrier population imbalance becomes significant in the strong field regime and it overcomes the intrinsic contribution. This finding clearly demonstrates that intrinsic transport properties of materials can be overwritten by external driving and may open a way to ultrafast optical-control of transport properties of materials.