22 Apr 2024 | Dongsung Choi, Masataka Mogi, Umberto De Giovannini, Doron Azoury, Baiqing Lv, Yifan Su, Hannes Hübener, Angel Rubio, Nuh Gedik
This paper reports the direct observation of Floquet-Bloch states in monolayer epitaxial graphene using time- and angle-resolved photoemission spectroscopy (trARPES) with mid-infrared pump excitation. The authors detect replicas of the Dirac cone, which are unequivocally shown to originate from the scattering between Floquet-Bloch states and photon-dressed free-electron-like photoemission final states, known as Volkov states. The evolution of these replica bands with pump polarization angle is analyzed, revealing that the rotation direction and speed of the arcs depend on the competition between Floquet-Bloch and Volkov states. Theoretical modeling supports the presence of Floquet-Bloch states by showing that the observed behavior cannot be fully explained by Volkov states alone. The study provides insights into the nature of Floquet-Bloch states in monolayer graphene and paves the way for further advancements in Floquet engineering in various quantum materials.This paper reports the direct observation of Floquet-Bloch states in monolayer epitaxial graphene using time- and angle-resolved photoemission spectroscopy (trARPES) with mid-infrared pump excitation. The authors detect replicas of the Dirac cone, which are unequivocally shown to originate from the scattering between Floquet-Bloch states and photon-dressed free-electron-like photoemission final states, known as Volkov states. The evolution of these replica bands with pump polarization angle is analyzed, revealing that the rotation direction and speed of the arcs depend on the competition between Floquet-Bloch and Volkov states. Theoretical modeling supports the presence of Floquet-Bloch states by showing that the observed behavior cannot be fully explained by Volkov states alone. The study provides insights into the nature of Floquet-Bloch states in monolayer graphene and paves the way for further advancements in Floquet engineering in various quantum materials.