Berry curvature signatures in chiroptical excitonic transitions
Samuel Beaulieu, Shuo Dong, Viktor Christiansson, Philipp Werner, Tommaso Pincelli, Jonas D. Ziegler, Takashi Taniguchi, Kenji Watanabe, Alexey Chernikov, Martin Wolf, Laurenz Rettig, Ralph Ernstorfer, Michael Schüler
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.