# Local Berry curvature signatures in dichroic angle-resolved photoelectron spectroscopy

## TL;DR

This paper demonstrates that circular dichroism ARPES can directly detect local Berry curvature signatures in topological materials, providing a new experimental approach to study their quantum geometry.

## Contribution

It introduces a novel method using dichroic ARPES to map local Berry curvature and spin properties in topological materials, supported by ab initio and model calculations.

## Key findings

- Circular dichroism ARPES reveals local Berry curvature signatures.
- Spin-resolved detection extends the method to spin-Chern insulators.
- The approach can be applied to out-of-equilibrium topological states.

## Abstract

Topologically nontrivial two-dimensional materials hold great promise for next-generation optoelectronic applications. However, measuring the Hall or spin-Hall response is often a challenge and practically limited to the ground state. An experimental technique for tracing the topological character in a differential fashion would provide useful insights. In this work, we show that circular dichroism angle-resolved photoelectron spectroscopy (ARPES) provides a powerful tool which can resolve the topological and quantum-geometrical character in momentum space. In particular, we investigate how to map out the signatures of the local Berry curvature by exploiting its intimate connection to the orbital angular momentum. A spin-resolved detection of the photoelectrons allows to extend the approach to spin-Chern insulators. Our predictions are corroborated by state-of-the art \emph{ab initio} simulations employing time-dependent density functional theory, complemented with model calculations. The present proposal can be extended to address topological properties in materials out of equilibrium in a time-resolved fashion.