Course 8 Transport at the atomic scale: Atomic and molecular contacts

Abstract

Publisher Summary This chapter presents an overview of some aspects of electron transport in atomic and molecular contacts. In the case of atomic contacts, the current fabrication capabilities and theoretical understanding are reaching a level of sophistication that has allowed accurate quantitative agreement between theory and experimental results for several properties. A key ingredient in this analysis is the concept of the mesoscopic PIN code—that is, the set of transmission Eigen values that determine all transport properties within the Landauer–Bfittiker picture. The results for atomic contacts are consistent with the idea of this set being determined by the valence orbital structure of each element. Superconducting transport has played a central role in these studies, providing a powerful tool to determine the PIN code by the subgap structure analysis. Conversely, atomic contacts have revealed themselves as an almost ideal system to verify the predictions of the microscopic theory of superconducting transport in the coherent multiple Andreev reflections (MAR) regime, which has been developed in the past decade.