Extracting the Transport Channel Transmissions in Scanning Tunneling Microscopy using the Superconducting Excess Current

TL;DR

This paper introduces a novel method using superconducting excess current to determine the transmission properties of atomic-scale junctions in scanning tunneling microscopy, complementing existing techniques.

Contribution

It presents a new approach to extract transport channel transmissions using superconducting excess current, combined with ab initio simulations for atomic junctions.

Findings

Superconducting excess current effectively reveals channel transmissions.

The method provides insights into how adjacent structures influence transport.

Atomic aluminum junctions were successfully analyzed with this technique.

Abstract

Transport through quantum coherent conductors, like atomic junctions, is described by the distribution of conduction channels. Information about the number of channels and their transmission can be extracted from various sources, such as multiple Andreev reflections, dynamical Coulomb blockade, or shot noise. We complement this set of methods by introducing the superconducting excess current as a new tool to continuously extract the transport channel transmissions of an atomic scale junction in a scanning tunneling microscope. In conjunction with ab initio simulations, we employ this technique in atomic aluminum junctions to determine the influence of the structure adjacent to the contact atoms on the transport properties.