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O: Fachverband Oberflächenphysik

O 96: Focus Session: Surface Transport at the Atomic Scale

O 96.5: Hauptvortrag

Freitag, 5. April 2019, 11:45–12:15, H15

Multiprobe STM measurements of electron transport at the atomic level — •Marek Kolmer, Wonhee Ko, and An-Ping Li — Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

Techniques based on multiprobe scanning tunneling microscopy (MP-STM) allow determination of electronic and spin transport in variety of systems supported on surfaces of solid materials. These MP-STM methods are currently considered as universal tools for in-situ characterization of mesoscopic transport phenomena in scales down to hundreds of nanometers. Alternatively, application of scanning tunneling potentiometry visualizes potential change during such mesoscopic charge current transport with a nominal nm resolution.

Here, we would like to discuss our efforts towards changing of this mesoscopic experimental paradigm by downscaling MP-STM experiments to the atomic level. In this case charge or spin current supplying probes are positioned in atomically defined locations with respect to the characterized nanosystem. Our experiments rely on fully STM-based tip positioning protocol with probe-to-probe separation distances reaching tens of nm. This is combined with about 5 pm vertical sensitivity in probe-to-system contact definitions. Those two factors enable realization of multiprobe scanning tunneling spectroscopy experiments, where transport properties could be characterized by macroscopic probes kept in well-defined tunneling conditions.

This research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.