Survival of Floquet–Bloch States in the Presence of Scattering

Nano Letters 21,12, 5028 - 5035 (2021)

Survival of Floquet–Bloch States in the Presence of Scattering

Sven Aeschlimann, Shunsuke A. Sato, Razvan Krause, Mariana Chávez-Cervantes, Umberto De Giovannini, Hannes Hübener, Stiven Forti, Camilla Coletti, Kerstin Hanff, Kai Rossnagel,Angel Rubio,, Isabella Gierz

Floquet theory has spawned many exciting possibilities for electronic structure control with light, with enormous potential for future applications. The experimental demonstration in solids, however, remains largely unrealized. In particular, the influence of scattering on the formation of Floquet− Bloch states remains poorly understood. Here we combine timeand angle-resolved photoemission spectroscopy with time-dependent density functional theory and a two-level model with relaxation to investigate the survival of Floquet−Bloch states in the presence of scattering. We find that Floquet−Bloch states will be destroyed if scatteringactivated by electronic excitationsprevents the Bloch electrons from following the driving field coherently. The two-level model also shows that Floquet−Bloch states reappear at high field intensities where energy exchange with the driving field dominates over energy dissipation to the bath. Our results clearly indicate the importance of long scattering times combined with strong driving fields for the successful realization of various Floquet phenomena.

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This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through CRC 925 (Project 170620586), CRC 1277 (Project 314695032), and the Cluster of Excellence “CUI: Advanced Imaging of Matter”. Further, the work received funding from the European Research Council (Starting Grant 851280 and Advanced Grant 694097), the European Union Graphene Flagship under Grant Agreement Nos. 785219 and 881603, Grupos Consolidados (IT1249-19), and JSPS KAKENHI (Grant Number JP20K14382). The Flatiron Institute is a division of the Simons Foundation.

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