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Strongfield and Ultrafast Physics at Graphene and Graphene-Based Interfaces

Kolloquium SFB 1083

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Abstract

When electrons in graphene are driven with intense laser fields, intraband currents and interband transitions may result. Intriguingly, these two processes can couple closely, leading to laser waveform-controlled excitations of currents. We will show the underlying dynamics, which is based on coherent subsequent Landau-Zener transitions and resulting in ultrafast turn-on times of currents (within 1 femtosecond). While this work refers to currents inside of graphene, we have also investigated how fast electrons can be transfered from the semimetal graphene into the wide bandgap semiconductor silicon carbide, a heterostructure representing a Schottky junction. We find that the charge transfer time can be as fast as 300 attoseconds. The last part of the talk will focus on experimentally disentangling virtual from real conduction band excitation, i.e., excitation alive during the presence of the laser pulse only from longlived excitations.

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