Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 119: Non-Equilibrium Daynamics in Light-Driven Materials: Theory Meets Experiment
O 119.4: Vortrag
Freitag, 16. März 2018, 12:15–12:30, MA 141
Photon-dressed states viewed by time- and angle-resolved photoemission spectroscopy — •Sven Aeschlimann1, Mariana Chavez-Cervantes1, Razvan Krause1, Camilla Coletti2, Kai Rossnagel3, and Isabella Gierz1 — 1Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg, Germany — 2Center for Nanotechnology @ NEST, Istituto Italiano di Tecnologia, Pisa, Italy — 3Institute of Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
According to Floquet theory, the coherent interaction between Bloch states and strong photon fields generates side bands of the unperturbed band structure with the possibility to induce topological phase transitions when time reversal symmetry is broken with circularly polarized light[1]. The effect has been observed in Bi2Se3 using tr-ARPES[2]. There are predictions for related phase transitions in graphene[1] and transition metal dichalcogenides[3].
We present evidence for the generation of photon-dressed states in graphene and WSe2 using tr-ARPES at extreme ultraviolet wavelengths. We discuss the key requirements for the experimental observation of these states, including the suppression of coherent interactions between the pump field and the photo-emitted electrons and a careful tuning of pump wavelength as well as pump and probe pulse durations.
[1] T. Oka and H. Aoki, PRB 79, 081406 (2009) [2] Y.H. Wang et al., Science 342, 453 (2013) [3] M. Claassen et al., Nature Communications 7, 13074 (2016)