Talk - Isabelle Gierz: Electron dynamics in low dimensions: a time- and momentum-resolved view
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Electron dynamics in low dimensions: a time- and momentum-resolved view
Tuesday May 24th, at 10.00
When reducing the dimensionality of a material electronic correlations become more and more important with dramatic effects on the electronic properties. Our goal is to engineer the electronic properties of various low-dimensional material systems with light, complementing the more traditional routes of electronic structure control using chemistry, pressure, or magnetic fields. Using the analogy with the Kapitza pendulum, I will show that driven systems are distinct from matter at equilibrium because the interaction with a periodic driving field results in the formation of new effective Hamiltonians with new eigenstates. Famous examples for electronic structure control by periodic driving include light-induced superconductivity in cuprates  and K3C60  using resonant excitation of the crystal lattice, as well as the formation of photon-dressed Floquet-Bloch states inducing a topological phase transition in Bi2Se3 .
I will present our time- and angle-resolved photoemission results on epitaxial monolayer and bilayer graphene for various driving regimes including interband excitation, free carrier absorption, and resonant phonon excitation.
 W. Hu et al., Nature Materials 13, 705 (2014)
 M. Mitrano et al., Nature 530, 461 (2016)
 Y. H. Wang et al. Science 342, 453 (2013)