How circular dichroism in time- and angle-resolved photoemission can be used to spectroscopically detect transient topological states in graphene

Schüler, Michael; Giovannini, Umberto De; Hübener, Hannes; Rubio, Angel; Sentef, Michael A.; Devereaux, Thomas P.; Werner, Philipp

doi:10.1103/PhysRevX.10.041013

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Journal article

How circular dichroism in time- and angle-resolved photoemission can be used to spectroscopically detect transient topological states in graphene

Schüler, Michael Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
Giovannini, Umberto De Nano-Bio Spectroscopy Group, Departamento de Fisica de Materiales, Universidad del País Vasco UPV/EHU- 20018 San Sebastián, Spain - Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
Hübener, Hannes Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
Rubio, Angel Nano-Bio Spectroscopy Group, Departamento de Fisica de Materiales, Universidad del País Vasco UPV/EHU- 20018 San Sebastián, Spain - Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany - Center for Computational Quantum Physics (CCQ), The Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
Sentef, Michael A. Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
Devereaux, Thomas P. Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA - Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
Werner, Philipp Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland

19.10.2020

Published in:

Physical Review X. - 2020, vol. 10, no. 4, p. 041013

English Pumping graphene with circularly polarized light is the archetype of light-tailoring topological bands. Realizing the induced Floquet-Chern-insulator state and demonstrating clear experimental evidence for its topological nature has been a challenge, and it has become clear that scattering effects play a crucial role. We tackle this gap between theory and experiment by employing microscopic quantum kinetic calculations including realistic electron-electron and electron-phonon scattering. Our theory provides a direct link to the build up of the Floquet-Chern- insulator state in light-driven graphene and its detection in time- and angle-resolved photoemission spectroscopy (ARPES). This approach allows us to study the robustness of the Floquet features against dephasing and thermalization effects. We also discuss the ultrafast Hall response in the laser-heated state. Furthermore, the induced pseudospin texture and the associated Berry curvature give rise to momentum-dependent orbital magnetization, which is reflected in circular dichroism in ARPES (CD-ARPES). Combining our nonequilibrium calculations with an accurate one-step theory of photoemission allows us to establish a direct link between the build up of the topological state and the dichroic pump-probe photoemission signal. The characteristic features in CD-ARPES are shown to be stable against heating and dephasing effects. Thus, tracing circular dichroism in time-resolved photoemission provides new insights into transient topological properties.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

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