Berry Curvature Signatures in Chiroptical Excitonic Transitions

TL;DR

This paper presents a novel method combining optical spectroscopy and photoemission techniques to detect Berry curvature effects in excitonic transitions of 2D materials, revealing their topological properties.

Contribution

It introduces a new experimental approach to measure Berry curvature signatures via energy- and momentum-resolved optical transitions in atomically thin materials.

Findings

Successful demonstration of Berry curvature signatures in WSe2

Method's robustness against ultrafast scattering processes

Excitons as probes of quantum geometrical properties

Abstract

The topology of the electronic band structure of solids can be described by its Berry curvature distribution across the Brillouin zone. We theoretically introduce and experimentally demonstrate a general methodology based on the measurement of energy- and momentum-resolved optical transition rates, allowing to reveal signatures of Berry curvature texture in reciprocal space. By performing time- and angle-resolved photoemission spectroscopy of atomically thin WSe$_2$ using polarization-modulated excitations, we demonstrate that excitons become an asset in extracting the quantum geometrical properties of solids. We also investigate the resilience of our measurement protocol against ultrafast scattering processes following direct chiroptical transitions.