Josephson current through randomly oriented CNTs

In this paper, we employ tunneling Hamiltonian formulation to obtain analytical expression for the Josephson current in (n, m) Carbon nanotubes (CNT) sandwiched between s-wave superconductors. For metallic tubes, we find that the dominant contribution to the Josephson current arises from modes crossing the Dirac points. Contribution from such conducting channels is independent of tube diameter of carbon nanotubes. Josephson current for each CNT is determined in terms of the spacing d between the superconductors, and the angle between the tube axis and the vector normal to the interface. Averaging over orientation angles gives the Josephson current through an assembly of randomly oriented CNTs, which turns out to be on the scale of 100 nA.

► Josephson current through carbon nano-tubes is dominated by few channels. ► Channels correspond to metallic modes passing through the underlying Dirac point. ► These are best seen in tunneling formulation.