Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 40: Focus Session: Charge Transport at Surfaces and Nanostructures with Multi-probe Techniques II

O 40.2: Vortrag

Dienstag, 21. März 2017, 14:30–14:45, WIL C307

New Perspectives in Scanning Tunneling Potentiometry — Philip Willke¹, Thomas Kotzott¹, Jan Voigt¹, Rainer G. Ulbrich¹, M. Alexander Schneider³, Thomas Pruschke², and •Martin Wenderoth¹ — ¹IV. Physikalisches Institut, Universität Göttingen, Göttingen, Germany — ²Institut für Theoretische Physik, Universität Göttingen, Göttingen, Germany — ³Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Erlangen, Germany

We present a new STP setup with a home-built low-temperature STM operating at 6 K and applicable magnetic field of up to 6 T. First, we study high-resolution STP of scattering centers on a sub-nanometer scale, especially the spatial evolution of the electrochemical potential for 1D defects in graphene.[1] We show that the voltage drop at a monolayer-bilayer boundary in graphene clearly extends spatially up to a few nanometers into the bilayer and hence is not located strictly at the structural defect. We explain this behaviour by the weak coupling between the two bilayer sheets extending the voltage drop at the interface due to the required current transfer. Second, we perform magnetotransport STP measurements mapping the local electrochemical potential as a function of the applied magnetic field.[2] Thus, we are able to extract graphene's charge carrier concentration locally by the emerging Hall field. Additionally, we show that the defect resistance of local defects such as steps, wrinkles and ML/BL-junctions remains constant for all magnetic fields. This work was supported by SPP 1459 'Graphene'. [1] P. Willke et al. Nature Commun. 6399 (2015) [2] P. Willke et al., under consideration (2016)