SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 105: Poster Session VIII: Graphene and beyond II
O 105.4: Poster
Donnerstag, 4. März 2021, 13:30–15:30, P
Probing Quantum Hall edge channels by scanning tunneling spectroscopy — •Tjorven Johnsen1, Sayanti Samaddar1, Astrid Weston2,3, Matthew J. Hamer2,3, Kenji Watanabe4, Takashi Taniguchi4, Roman Gorbachev2,3,5, and Markus Morgenstern1 — 1II. Institute of Physics B, RWTH Aachen University, Germany. — 2Department of Physics and Astronomy, University of Manchester, UK. — 3National Graphene Institute, University of Manchester, UK. — 4National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan. — 5Henry Royce Institute for Advanced Materials, University of Manchester, UK.
The topology of the quantum Hall effect is imprinted in the edge channel (EC) transport, but microscopic details of the EC topography at the scale of the magnetic length are largely unknown. Here we use scanning tunneling spectroscopy to probe the quantum Hall ECs at integer fillings along a gate-tunable graphene pn interface. ECs with finite width at the Fermi level become apparent along the continuous potential gradient across the interface. They meander along the interface in width and lateral position due to the inhomogeneous local electrostatic environment. However, the appearance of charging lines testifies the simultaneous presence of a tip-induced quantum dot that is influencing the electrostatics at the interface similarly as in scanning gate experiments and, hence, modifies the measurement results in detail. To disentangle the contributions from ECs and quantum dot, we employed electrostatic model simulations that explain multiple details of the observed charging lines and the local density of states features.