CPM Seminar

Force and current at atomic scale: do we sense the same entity?

Pavel Jelinek

Institute of Physics of the Academy of Science, Czech Republic

At atomic scale, both the chemical force and the current between two objects are determined by an overlap of their wavefunctions. Therefore, one can expect the quantities are interdependent. Recently, a combination of scanning tunneling (STM) and atomic force microscopy (AFM) in a single instrument brings an opportunity to correlate directly the chemical forces with simultaneously measured tunneling currents at the atomic scale.

In this talk, we will present a simple theoretical model describing the relation between the chemical force and current. We will also discuss key effects playing an important role during the formation of the atomic contact between tip and sample and the electron transport through. We combine STM/AFM measurements with DFT calculations to shed light on factors playing an important role in atomic contact formation such as (i) a structural relaxation; (ii) a modification of the electronic structure; (iii) a collapse of the tunneling barrier; (iv) the importance of elastic multiple-scattering processes of electrons; and (v) modification of surface dipoles.