SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 72: Mini-Symposium: Coherent band structure engineering with light II
O 72.5: Vortrag
Mittwoch, 3. März 2021, 15:00–15:15, R2
Observing Light-Induced Floquet Band Gaps in the Longitudinal Conductivity of Graphene — •Lukas Broers1,2 and Ludwig Mathey1,2,3 — 1Center for Optical Quantum Technologies, University of Hamburg, 22761 Hamburg, Germany — 2Institute for Laser Physics, University of Hamburg, 22761 Hamburg, Germany — 3The Hamburg Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
We propose optical longitudinal conductivity as a realistic observable to detect light-induced Floquet band gaps in graphene. These gaps manifest as resonant features in the conductivity, when resolved with respect to the probing frequency and the driving field strength. We demonstrate these features via a dissipative master equation approach which gives access to a frequency- and momentum-resolved electron distribution. This distribution follows the light-induced Floquet-Bloch bands, resulting in a natural interpretation as occupations of these bands. Furthermore, we show that there are population inversions of the Floquet-Bloch bands at the band gaps for sufficiently strong driving field strengths. This strongly reduces the conductivity at the corresponding frequencies. Therefore our proposal puts forth not only an unambiguous demonstration of light-induced Floquet-Bloch bands, which advances the field of Floquet engineering in solids, but also points out the control of transport properties via light, that derives from the electron distribution on these bands.