Chiroptical Valleytronic in SnSe
Abstract
Quantum geometric properties of Bloch electrons play a central role in governing light-matter interactions and transport phenomena in solids. Here, we report quantum-geometric chiroptical selection rules that generate a helicity-dependent momentum-space population imbalance in the group-IV monochalcogenide SnSe. By combining time- and angle-resolved extreme-ultraviolet photoemission spectroscopy with ab initio real-time simulations of photoexcited carrier dynamics, we identify valley-selective excitation at opposite crystal momenta arising from the breaking of time-reversal symmetry under circularly polarized illumination. We theoretically demonstrate that the magnitude of valley circular dichroism is strongly constrained by crystal symmetry through its influence on the quantum geometric tensor, the key quantity underlying valley optical selection rules. The resulting chiroptically induced valley polarization decays on sub-picosecond timescales through intervalley scattering mediated by electron-phonon coupling. Furthermore, we show theoretically that the population imbalance between valleys at opposite momenta gives rise to a helicity-reversible transient photocurrent. These findings provide microscopic insight into how quantum geometry governs valley-selective light-matter interactions, valley polarization, and photocurrent generation in van der Waals materials exhibiting hidden and transient symmetry breaking.
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BibTeX
@misc{pan2026chiroptical,
title = {{Chiroptical Valleytronic in SnSe}},
author = {Yiming Pan and Sotirios Fragkos and Umberto Dellasette and Quentin Courtade and Dominique Descamps and Stéphane Petit and Fabio Caruso and Samuel Beaulieu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.30930},
eprint = {2610.30930},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.30930},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Chiroptical Valleytronic in SnSe
AU - Yiming Pan
AU - Sotirios Fragkos
AU - Umberto Dellasette
AU - Quentin Courtade
AU - Dominique Descamps
AU - Stéphane Petit
AU - Fabio Caruso
AU - Samuel Beaulieu
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.30930
UR - https://arxiv.org/abs/2610.30930
AB - Quantum geometric properties of Bloch electrons play a central role in governing light-matter interactions and transport phenomena in solids. Here, we report quantum-geometric chiroptical selection rules that generate a helicity-dependent momentum-space population imbalance in the group-IV monochalcogenide SnSe. By combining time- and angle-resolved extreme-ultraviolet photoemission spectroscopy with ab initio real-time simulations of photoexcited carrier dynamics, we identify valley-selective excitation at opposite crystal momenta arising from the breaking of time-reversal symmetry under circularly polarized illumination. We theoretically demonstrate that the magnitude of valley circular dichroism is strongly constrained by crystal symmetry through its influence on the quantum geometric tensor, the key quantity underlying valley optical selection rules. The resulting chiroptically induced valley polarization decays on sub-picosecond timescales through intervalley scattering mediated by electron-phonon coupling. Furthermore, we show theoretically that the population imbalance between valleys at opposite momenta gives rise to a helicity-reversible transient photocurrent. These findings provide microscopic insight into how quantum geometry governs valley-selective light-matter interactions, valley polarization, and photocurrent generation in van der Waals materials exhibiting hidden and transient symmetry breaking.
ER -