Observation of Floquet states in graphene

Merboldt, Marco

dc.contributor.advisor	Mathias, Stefan Prof. Dr.
dc.contributor.author	Merboldt, Marco
dc.date.accessioned	2025-09-17T17:46:15Z
dc.date.issued	2025-09-17
dc.identifier.uri	http://resolver.sub.uni-goettingen.de/purl?ediss-11858/16235
dc.identifier.uri	http://dx.doi.org/10.53846/goediss-11509
dc.format.extent	197	de
dc.language.iso	eng	de
dc.subject.ddc	530	de
dc.title	Observation of Floquet states in graphene	de
dc.type	doctoralThesis	de
dc.contributor.referee	Mathias, Stefan Prof. Dr.
dc.date.examination	2025-01-30	de
dc.subject.gok	Physik (PPN621336750)	de
dc.description.abstracteng	Recent advances in the field of condensed-matter physics have unlocked the potential to realize and control emergent material phases that are not accessible in thermal equilibrium. One of the most promising concepts in this regard is Floquet engineering, the coherent dressing of matter via time-periodic perturbations. However, the broad applicability of Floquet engineering to quantum materials is still in question. Crucially, the theoretically predicted Floquet-induced effects in monolayer graphene, the most sought-after case, could not be verified or only be explored in indirect experimental approaches. More specifically, a report of the light-induced anomalous Hall effect in graphene is critically debated. Furthermore, a time-resolved photoemission experiment even indicates that Floquet effects might not be realizable in graphene and other (semi-)metals that exhibit relatively short decoherence times. Here, we resolve this long-standing debate by using electronic structure measurements to provide direct experimental evidence of Floquet engineering in graphene. We report light-matter-dressed Dirac bands by measuring the contribution of Floquet sidebands, Volkov sidebands, and their quantum path interference to graphene’s photoemission spectral function. Fully supported by experiment and theory, we demonstrate that Floquet engineering in graphene is possible, even though ultrafast decoherence processes occur on few tens of femtosecond timescales. Our results pave the way for the experimental realization of Floquet engineering strategies in (semi-)metallic systems, promising the coherent stabilization of light-induced states with potentially non-trivial topological properties.	de
dc.contributor.coReferee	Manmana, Salvatore R. PD Dr.
dc.subject.eng	Ultrafast momentum microscopy	de
dc.subject.eng	trARPES	de
dc.subject.eng	Graphene	de
dc.subject.eng	light-matter interaction	de
dc.subject.eng	Floquet engineering	de
dc.subject.eng	Floquet-Bloch	de
dc.subject.eng	Dirac materials	de
dc.subject.eng	Non-equilibrium quantum phases	de
dc.subject.eng	Time-periodic driving	de
dc.subject.eng	Ultrafast dynamics	de
dc.subject.eng	Condensed-matter physics	de
dc.identifier.urn	urn:nbn:de:gbv:7-ediss-16235-3
dc.date.embargoed	2026-01-29
dc.affiliation.institute	Fakultät für Physik	de
dc.description.embargoed	2026-01-29	de
dc.identifier.ppn	1936215837
dc.notes.confirmationsent	Confirmation sent 2025-09-17T19:45:01	de

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