Multiple Andreev reflection in single atom niobium junctions
Abstract
Single atom junctions between superconducting niobium leads are produced using the Mechanically Controllable Break Junction technique. The current-voltage characteristics of these junctions are analysed using an exact formulation for a superconducting quantum point contact. For tunnelling between two single atoms with a sufficiently large vacuum barrier, it is found that a single channel dominates the current, and that the current-voltage characteristic is described by the theory, without adjustable parameters. For a contact of a single Nb atom it is shown that five conductance channels contribute to the conductance, in agreement with the number expected based on the number of valence orbitals for this d-metal. For each of the channels the transmission probability is obtained from the fits and the limits of accuracy for these numbers are discussed.
Cite
@article{arxiv.cond-mat/9908223,
title = {Multiple Andreev reflection in single atom niobium junctions},
author = {B. Ludoph and N. van der Post and E. N. Bratus' and E. V. Bezuglyi and V. S. Shumeiko and G. Wendin and J. M. van Ruitenbeek},
journal= {arXiv preprint arXiv:cond-mat/9908223},
year = {2009}
}
Comments
11 pages; submitted to Phys. Rev. B