Visualizing Berry curvature in a Floquet-Chern insulator
Abstract
Circularly polarized light can open a topological gap in a gapless Dirac system, creating a Floquet-Chern insulator. However, its Berry curvature has not been directly resolved. Here we use circular-dichroism time- and angle-resolved photoemission spectroscopy (Tr-ARPES) to map the light-induced Berry curvature of Floquet-Bloch states on the surface of Bi2Se3. By comparing spectra for opposite helicities of the mid-infrared pump, we isolate the induced geometric response. We observe alternating-sign Berry-curvature features at Floquet gaps that repeat at intervals set by the pump photon energy and redistribute with pump field strength in agreement with calculations for a periodically driven Dirac Hamiltonian. Both the induced Berry-curvature and the Floquet Dirac gap decay faster than the replica intensity, showing that spectral replicas can persist even after coherent Floquet hybridization weakens. These results establish momentum-resolved Berry-curvature mapping as a direct probe of light-induced topology and coherent Floquet band formation.
Related
- Chiral p-Wave Superconductivity Proximate to a Fractional Chern Insulator and a Topological Charge Density Wave in a Moiré Chern Band
- Superlattice-Stabilized Fractional Chern Insulators in a "Berry Basin" Model
- Optical control of electrons in a Floquet topological insulator
- Vacancy-driven topological transition of a Chern insulator
- Dynamical transition in non-Hermitian Chern insulator
BibTeX
@misc{kim2026visualizing,
title = {{Visualizing Berry curvature in a Floquet-Chern insulator}},
author = {Younsik Kim and Rishi Acharya and Hannah E. Aguirre and Lucca Figari and Daniel P. Shoemaker and Fahad Mahmood},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.17500},
eprint = {2609.17500},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.17500},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Visualizing Berry curvature in a Floquet-Chern insulator
AU - Younsik Kim
AU - Rishi Acharya
AU - Hannah E. Aguirre
AU - Lucca Figari
AU - Daniel P. Shoemaker
AU - Fahad Mahmood
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.17500
UR - https://arxiv.org/abs/2609.17500
AB - Circularly polarized light can open a topological gap in a gapless Dirac system, creating a Floquet-Chern insulator. However, its Berry curvature has not been directly resolved. Here we use circular-dichroism time- and angle-resolved photoemission spectroscopy (Tr-ARPES) to map the light-induced Berry curvature of Floquet-Bloch states on the surface of Bi_2Se_3. By comparing spectra for opposite helicities of the mid-infrared pump, we isolate the induced geometric response. We observe alternating-sign Berry-curvature features at Floquet gaps that repeat at intervals set by the pump photon energy and redistribute with pump field strength in agreement with calculations for a periodically driven Dirac Hamiltonian. Both the induced Berry-curvature and the Floquet Dirac gap decay faster than the replica intensity, showing that spectral replicas can persist even after coherent Floquet hybridization weakens. These results establish momentum-resolved Berry-curvature mapping as a direct probe of light-induced topology and coherent Floquet band formation.
ER -