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O: Fachverband Oberflächenphysik

O 72: Mini-Symposium: Coherent band structure engineering with light II

O 72.1: Invited Talk

Wednesday, March 3, 2021, 13:30–14:00, R2

On the survival of Floquet-Bloch states in the presence of scattering — •Isabella Gierz — University of Regensburg, Institute for Experimental an Applied Physics

Floquet theory has spawned many exciting possibilities for electronic structure control. The experimental realization in solids, however, still largely remains pending. Despite the enormous potential for future applications, the influence of scattering on the formation of Floquet-Bloch states remains poorly understood. Here we combine time- and angle-resolved photoemission spectroscopy (tr-ARPES) with time-dependent density functional theory (TDDFT) and a simple two-level system with dissipation 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 system 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.