Academic Affiliation: Georg‐August‐University of Göttingen

Talk: November 29, 2018

Scanning Tunneling Potentiometry: Mapping local transport field on the atomic scale

Information on local transport fields in an inhomogeneous system are a prerequisite to bridge the length scale on which different transport concepts have their validity like the Boltzmann theory for macroscopic systems or the Landauer theory of local transport fields in the vicinity of scattering centers.
Scanning tunneling Potentiometry (STP) has opened up the unique capability to combine atomic scale transport properties with structural information of a scanning tunneling microscope (STM) down to the atomic scale.
The basic idea of STP is to use the tip of an STM as a weakly coupled, non-invasive voltage probe to determine the spatial variation of the local electrochemical potential (x,y) on a surface of a current carrying sample. This quantity characterizes the energy level filling of the electrons in a non-equilibrium situation and its gradient will (constant density of carriers assumed) describe local electric fields connected with the electric transport. Several examples are presented, e.g. local variations of the electrochemical potential due to charge transport of biased samples down to Angstrom length scales have been determined.