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HL: Fachverband Halbleiterphysik
HL 40: Thermal, acoustic and transport properties
HL 40.3: Vortrag
Mittwoch, 18. März 2020, 10:00–10:15, POT 151
Probing curling of current induced electric field in real space in graphene using KPFM — •Sayanti Samaddar1, Kevin Janßen1,2, Tjorven Johnsen1, Zhengzhing Wang3, Daniel Neumaier3, Marcus Liebmann1, and Markus Morgenstern1 — 1II. Institute of Physics B, RWTH Aachen University and JARA-FIT, Otto-Blumenthal-Str., 52074 Aachen, Germany — 2Peter Grünberg Institute (PGI-6,9), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — 3Advanced Microelectronic Center Aachen (AMICA), AMO GmbH, Otto-Blumenthal-Str. 25, 52074 Aachen
We conduct local transport measurements using Kelvin Probe Force Microscopy (KPFM) to investigate gated single layer graphene on SiN (150 nm)/Si substrate at room temperature. This allows us to image two quantities: (1) doping fluctuations and (2) local electric fields due to electric current. As charge neutrality is approached, the initially homogeneous and uniformly directed electric field lines start developing prominent curvature that ultimately lead to inversion at certain locations that are dominated by short range scattering. The inverted electric field implies a local back flow of current i.e. formation of current vortices. These current vortices systematically disappear at high source to drain current. Since vortex formation could be a manifestation of viscous flow of electrons [1], we investigate the plausibility of a hydrodynamic description by deducing the relevant transport length scales, from the gate dependent electric field maps at large gate voltages, taking different possible scattering mechanisms into account.
[1] D.A. Bandurin et al., Science 351, 1055-1057 (2016)