Low-Energy Electron Potentiometry: Contactless Imaging of Charge Transport on the Nanoscale.
Charge transport measurements form an essential tool in condensed matter physics. The usual approach is to contact a sample by two or four probes, measure the resistance and derive the resistivity, assuming homogeneity within the sample. A more thorough understanding, however, requires knowledge of local resistivity variations. Spatially resolved information is particularly important when studying novel materials like topological insulators, where the current is localized at the edges, or quasi-two-dimensional (2D) systems, where small-scale variations can determine global properties. Here, we demonstrate a new method to determine spatially-resolved voltage maps of current-carrying samples. This technique is based on low-energy electron microscopy (LEEM) and is therefore quick and non-invasive. It makes use of resonance-induced contrast, which strongly depends on the local potential. We demonstrate our method using single to triple layer graphene. However, it is straightforwardly extendable to other quasi-2D systems, most prominently to the upcoming class of layered van der Waals materials.
Leiden University, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, Netherlands.
J
J
Kautz
Leiden University, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, Netherlands.
J
J
Jobst
Lehrstuhl für Angewandte Physik, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
C
C
Sorger
IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, New York 10598, US.|Leiden University, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, Netherlands.
R M
RM
Tromp
Lehrstuhl für Angewandte Physik, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
H B
HB
Weber
Leiden University, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, Netherlands.
S J
SJ
van der Molen