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O: Fachverband Oberflächenphysik
O 105: Poster Session VIII: Graphene and beyond II
O 105.5: Poster
Thursday, March 4, 2021, 13:30–15:30, P
Local spots of viscous electron flow in graphene at room temperature and moderate mobility — •Sayanti Samaddar1, Jeff Strassdas1, Kevin Janßen2, Tjorven Johnsen1, Zhenxing Wang3, Daniel Nuemaier3,4, Marcus Liebmann1, and Markus Morgenstern1 — 1II. Institute of Physics B, RWTH Aachen University and JARA-FIT, Otto-Blumenthal-Str., 52074 Aachen, Germany — 2Research Centre Jülich, Peter Grünberg Institute, 52425 Jülich, Germany, — 3Advanced Microelectronic Center Aachen (AMICA), AMO GmbH, Otto-Blumenthal-Str. 25, 52074 Aachen — 4University of Wuppertal, 42285 Wuppertal, Germany,
Dominating electron-electron scattering enables viscous electron flow exhibiting hydrodynamic current density patterns such as Poiseuille profiles or vortices. The viscous regime has recently been observed in graphene by non-local transport experiments and mapping of Poiseuille profiles up to room temperature. Here, we probe the current-induced surface potential maps of graphene field effect transistors using scanning probe microscopy at room temperature. We discover the appearance of μm large areas close to charge neutrality, where the current induced electric field opposes the externally applied field. By estimating the scattering lengths from the gate dependence of local electric fields, we find that these areas exhibit a dominating electron-electron scattering as expected for viscous flow. We map the respective meandering electric fields and carefully rule out artifacts such as by source-drain voltage induced local doping. Our results imply that viscous electron flow is omnipresent in graphene devices, even at moderate mobility.