Abstract
We propose a realistic regime to detect the light-induced topological band gap in graphene via time-resolved angle-resolved photoelectron spectroscopy (trARPES), that can be achieved with current technology. The direct observation of Floquet-Bloch bands in graphene is limited by low-mobility, Fourier-broadening, laser-assisted photoemission (LAPE), probe-pulse energy-resolution bounds, space-charge effects and more. We characterize a regime of low driving frequency and high amplitude of the circularly polarized light that induces an effective band gap at the Dirac point that exceeds the Floquet zone. This circumvents limitations due to energy resolutions and band broadening. The electron distribution across the Floquet replica in this limit allow for distinguishing LAPE replica from Floquet replica. We derive our results from a dissipative master equation approach that gives access to two-point correlation functions and the electron distribution relevant for trARPES measurements.
Highlights
Floquet engineering constitutes a novel approach to control material properties via light [1,2,3,4]
We discuss the dependence of our predictions on the system parameters, how they affect the systematic limitations of the energy resolution of photoemission spectroscopy
We have pointed out a realistic regime for the detection of the light-induced topological gap in graphene via time- and angle-resolved photoelectron spectroscopy
Summary
Floquet engineering constitutes a novel approach to control material properties via light [1,2,3,4]. We discuss the dependence of our predictions on the system parameters, how they affect the systematic limitations of the energy resolution of photoemission spectroscopy These parameters include the driving frequency and field strength, which determine the Floquet-Bloch band structure, the dissipation coefficients that broaden the band signals, and the pulse lengths of drive and probe lasers. The graphene sample is probed by a tunable extreme ultraviolet laser pulse from the same direction It has a shorter pulse length and excites photoelectrons out of the driven graphene over a time span during which the driving intensity is approximately constant. This is necessary for resolving the time-dependent Floquet-Bloch bands, which are sensitive to the driving amplitude. For simplicity this is denoted as k in the following
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