Proximity effect in superconductor–carbon nanotube–superconductor tunnel junctions

Abstract

We have studied the proximity effect in a short superconductor-carbon nanotube-superconductor (S/CN/Sl junction made of a metallic carbon nanotube embedded between two conventional superconducting electrodes. It is found that some junctions possess constant supercurrents, while others have oscillating supercurrents with increasing nanotube length. Moreover, unlike superconductor-normal metal-superconductor (S/N/S) junctions, the S/CN/S junctions have fixed open channels and therefore. fixed critical supercurrents with increasing nanotube diameter. Especially, the chiral symmetry effects of the carbon nanotubes are well reflected in the dependence of the critical supercurrent on the Fermi level, from which an experimental method to explicitly measure the chiral angle of a nanotube is suggested.