Nonlinear dynamics and time-resolved spectroscopy in graphene investigated at the free-electron laser FELBE

The FELBE free-electron laser delivers intense THz and mid infrared pulses that are ideal to excite various low-energy quasipartcles in solids and to study their ultrafast dynamics [1]. We present the capabilities in the FELBE laboratories for degenerate and two-color pump-probe experiments, four-wave mixing and time-resolved near-field experiments. As an example, we show how nonlinear intraband transport in bilayer graphene manifests itself in polarization resolved pump-probe experiments [2]. Polarization resolved pump-probe experiments furthermore shed light into the microscopic scattering mechanisms, allowing us to disentangle Coulomb and phonon-related scattering processes [3].
[1] M. Helm, S. Winnerl, A. Pashkin, J. M. Klopf, J.-C. Deinert, S. Kovalev, P. Evtushenko, U. Lehnert, R. Xiang, A. Arnold, A. Wagner, S. M. Schmidt, U. Schramm, T. Cowan & P. Michel, Eur. Phys. J. Plus 138, 158 (2023).
[2] A. Seidl, R. Anvari, M. M. Dignam, P. Richter, T. Seyller, H. Schneider, M. Helm, and S. Winnerl Phys. Rev. B 105, 085404 (2022).
[3] J. C. König-Otto, M. Mittendorff, T. Winzer, F. Kadi, E. Malic, A. Knorr, C. Berger, W. A. de Heer, A. Pashkin, H. Schneider, M. Helm, and S. Winnerl, Phys. Rev. Lett. 117, 087401 (2016).