Floquet-Bloch valleytronics

Abstract Upon time-periodic driving of electrons using electromagnetic fields, the emergence of Floquet-Bloch states enables the creation and control of exotic quantum phases. In transition metal dichalcogenides, broken inversion symmetry within each monolayer results in Berry curvature at the K and...

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Main Authors: Sotirios Fragkos, Baptiste Fabre, Olena Tkach, Stéphane Petit, Dominique Descamps, Gerd Schönhense, Yann Mairesse, Michael Schüler, Samuel Beaulieu
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-61076-7
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author Sotirios Fragkos
Baptiste Fabre
Olena Tkach
Stéphane Petit
Dominique Descamps
Gerd Schönhense
Yann Mairesse
Michael Schüler
Samuel Beaulieu
author_facet Sotirios Fragkos
Baptiste Fabre
Olena Tkach
Stéphane Petit
Dominique Descamps
Gerd Schönhense
Yann Mairesse
Michael Schüler
Samuel Beaulieu
author_sort Sotirios Fragkos
collection DOAJ
description Abstract Upon time-periodic driving of electrons using electromagnetic fields, the emergence of Floquet-Bloch states enables the creation and control of exotic quantum phases. In transition metal dichalcogenides, broken inversion symmetry within each monolayer results in Berry curvature at the K and K′ valley extrema, giving rise to chiroptical selection rules that are fundamental to valleytronics. Here, we bridge the gap between these two concepts and introduce Floquet-Bloch valleytronics. Using time- and polarization-resolved extreme ultraviolet momentum microscopy combined with state-of-the-art ab initio theory, we demonstrate the formation of valley-polarized Floquet-Bloch states in 2H-WSe2 upon below-bandgap driving with circularly polarized light pulses. We investigate quantum-path interference between Floquet-Bloch and Volkov states, revealing its dependence on the valley pseudospin and light polarization. Extreme ultraviolet photoemission circular dichroism in these non-equilibrium settings reveals the potential for controlling the orbital character of Floquet-engineered states. These findings link Floquet engineering and quantum-geometric light-matter coupling in two-dimensional materials.
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spelling doaj-art-cc2940089fe84d4c9d7a6dcc3d1e7bfc2025-08-20T03:03:29ZengNature PortfolioNature Communications2041-17232025-07-0116111010.1038/s41467-025-61076-7Floquet-Bloch valleytronicsSotirios Fragkos0Baptiste Fabre1Olena Tkach2Stéphane Petit3Dominique Descamps4Gerd Schönhense5Yann Mairesse6Michael Schüler7Samuel Beaulieu8Université de Bordeaux - CNRS - CEA, CELIA, UMR5107Université de Bordeaux - CNRS - CEA, CELIA, UMR5107Johannes Gutenberg-Universität, Institut für PhysikUniversité de Bordeaux - CNRS - CEA, CELIA, UMR5107Université de Bordeaux - CNRS - CEA, CELIA, UMR5107Johannes Gutenberg-Universität, Institut für PhysikUniversité de Bordeaux - CNRS - CEA, CELIA, UMR5107PSI Center for Scientific Computing, Theory and DataUniversité de Bordeaux - CNRS - CEA, CELIA, UMR5107Abstract Upon time-periodic driving of electrons using electromagnetic fields, the emergence of Floquet-Bloch states enables the creation and control of exotic quantum phases. In transition metal dichalcogenides, broken inversion symmetry within each monolayer results in Berry curvature at the K and K′ valley extrema, giving rise to chiroptical selection rules that are fundamental to valleytronics. Here, we bridge the gap between these two concepts and introduce Floquet-Bloch valleytronics. Using time- and polarization-resolved extreme ultraviolet momentum microscopy combined with state-of-the-art ab initio theory, we demonstrate the formation of valley-polarized Floquet-Bloch states in 2H-WSe2 upon below-bandgap driving with circularly polarized light pulses. We investigate quantum-path interference between Floquet-Bloch and Volkov states, revealing its dependence on the valley pseudospin and light polarization. Extreme ultraviolet photoemission circular dichroism in these non-equilibrium settings reveals the potential for controlling the orbital character of Floquet-engineered states. These findings link Floquet engineering and quantum-geometric light-matter coupling in two-dimensional materials.https://doi.org/10.1038/s41467-025-61076-7
spellingShingle Sotirios Fragkos
Baptiste Fabre
Olena Tkach
Stéphane Petit
Dominique Descamps
Gerd Schönhense
Yann Mairesse
Michael Schüler
Samuel Beaulieu
Floquet-Bloch valleytronics
Nature Communications
title Floquet-Bloch valleytronics
title_full Floquet-Bloch valleytronics
title_fullStr Floquet-Bloch valleytronics
title_full_unstemmed Floquet-Bloch valleytronics
title_short Floquet-Bloch valleytronics
title_sort floquet bloch valleytronics
url https://doi.org/10.1038/s41467-025-61076-7
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AT stephanepetit floquetblochvalleytronics
AT dominiquedescamps floquetblochvalleytronics
AT gerdschonhense floquetblochvalleytronics
AT yannmairesse floquetblochvalleytronics
AT michaelschuler floquetblochvalleytronics
AT samuelbeaulieu floquetblochvalleytronics