Ab-intio study of ultrafast charge dynamics in graphene
- URL: http://arxiv.org/abs/2012.00435v2
- Date: Wed, 6 Jan 2021 12:16:17 GMT
- Title: Ab-intio study of ultrafast charge dynamics in graphene
- Authors: Q. Z. Li, P. Elliott, J. K. Dewhurst, S. Sharma, S. Shallcross
- Abstract summary: We show that the transient electron momentum density provides an excellent description of momentum excitation charge.
For even the most intense laser pulses we find that the electron dynamics to be almost completely dominated by the $pi$-band.
- Score: 0.0
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: Monolayer graphene provides an ideal material to explore one of the
fundamental light-field driven interference effects: Landau-Zener-St\"uckelberg
interference. However, direct observation of the resulting interference
patterns in momentum space has not proven possible, with
Landau-Zener-St\"uckelberg interference observed only indirectly through
optically induced residual currents. Here we show that the transient electron
momentum density (EMD), an object that can easily be obtained in experiment,
provides an excellent description of momentum resolved charge excitation. We
employ state-of-the-art time-dependent density function theory calculations,
demonstrating by direct comparison of EMD with conduction band occupancy,
obtained from projecting the time propagated wavefunction onto the ground
state, that the two quantities are in excellent agreement. For even the most
intense laser pulses we find that the electron dynamics to be almost completely
dominated by the $\pi$-band, with transitions to other bands strongly
suppressed. Simple model based tight-binding approaches can thus be expected to
provide an excellent description for the laser induced electron dynamics in
graphene.
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