Interaction corrections to tunneling conductance in ballistic superconductors

TL;DR

This paper investigates how interaction corrections affect tunneling conductance in ballistic superconductors, revealing a broader fluctuation region and novel power-law behavior near the transition, with potential experimental implications.

Contribution

It extends the understanding of fluctuation corrections from diffusive to ballistic superconductors, highlighting new power-law effects and a broader fluctuation regime.

Findings

Correction remains negative and logarithmic away from critical temperature.

Near the transition, a novel power-law for the Maki-Thompson contribution is found.

The fluctuation region is significantly broader in ballistic superconductors.

Abstract

It is known that in the two-dimensional disordered superconductors electron-electron interactions in the Cooper channel lead to the negative logarithmic in temperature correction to the tunneling conductance above the critical temperature. Physically this result appears due to the density of states suppression by superconductive fluctuations near the Fermi level. It is interesting that the other correction, which accounts for the Maki-Thompson-type interaction of fluctuations, is positive and exhibits strong power law, which dominates the logarithmic term in the immediate vicinity of the critical temperature. An interplay between these two contributions determines the zero-bias anomaly in fluctuating superconductors. This paper is devoted to the fate of such interaction corrections in the ballistic superconductors. It turns out that ballistic dynamic fluctuations perturb single-particle density of states near the Fermi level at the energy scale which is different from that in the diffusive case. As the consequence, fluctuation region becomes much broader. In this regime we confirm that correction to the tunneling conductance remains negative and logarithmic not too close to the critical temperature while in the immediate vicinity of the transition we find novel power law for the Maki-Thompson contribution. It is suggested that peculiar non-monotonous temperature dependence of the tunneling conductance may be probed via magneto-tunnel experiments.