Electronic Transport on the Nanoscale: Ballistic Transmission and Ohm’s Law

Abstract

If a current of electrons flows through a normal conductor (in contrast to a superconductor), it is impeded by local scattering at defects as well as phonon scattering. Both effects contribute to the voltage drop observed for a macroscopic complex system as described by Ohm's law. Although this concept is well established, it has not yet been measured around individual defects on the atomic scale. We have measured the voltage drop at a monatomic step in real space by restricting the current to a surface layer. For the Si(111)-( [see text]3 x [see text]3)-Ag surface a monotonous transition with a width below 1 nm was found. A numerical analysis of the data maps the current flow through the complex network and the interplay between defect-free terraces and monatomic steps.

Spatial extent of a Landauer residual-resistivity dipole in graphene quantified by scanning tunnelling potentiometry

“…1a). This voltage V STP ¼ m ECP e has been referred to as the local ECP, which is here inherently defined by the STP method 2,6,31 . The measurements are made at different values of the electron current in the sample plane, especially at zero and forward and reversed current as defined by the potential applied to the sample contacts.…”

“…In contrast, non-equilibrium phenomena of electronic transport on the atomic scale are less well explored experimentally. Such measurements have been carried out at two-dimensional conductors 2,3 , graphene being a recent prominent system [4][5][6][7][8] . The experiments demonstrated the influence of non-local scattering processes (for example, electronphonon or electron-electron scattering) in defect-free sample regions as well as electron scattering at localized defects like steps, interfaces and grain boundaries.…”

Local fields in conductor surface electromigration: A first-principles study in the low-bias ballistic limit

“…22,33 Due to this correlation, strong external field inhomogeneities are shown to often arise within a screening length surrounding an atomic defect (as illustrated in Fig. 1) and act to drive EM.…”

Energy Gap Induced by Friedel Oscillations Manifested as Transport Asymmetry at Monolayer-Bilayer Graphene Boundaries

“…We directly measure the voltage drop across a ML-BL graphene boundary by using a scanning-tunnelingpotentiometry (STP) technique [16][17][18], implemented in a cryogenic multiple-probe scanning tunneling microscope (STM) [19,20]. In the STP setup that is schematically shown in Fig.…”

“…2(a), two STM probes (probe 1 and probe 2) are in contact with the sample surface, applying a constant current. A third tip (probe 3) is positioned between the current probes and scans the sample surface to measure both the topography and the local electrochemical potential (μ ec ) at each point [18,19,21] at 80 K. Both sample and tip are maintained at the same temperature.…”