Interaction corrections to tunneling conductance 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 logarithmical in temperature correction to the tunneling conductance, δgDOS∝−ln(TcT−Tc), above the critical temperature Tc. 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, δgMT∝(TcT−Tc)3, 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 Brief Report is devoted to the fate of such interaction corrections in the ballistic superconductors. It turns out that ballistic dynamic fluctuations perturb the single-particle density of states near the Fermi level at the energy scale ϵ∼Tc(T−Tc), which is different from ϵ∼T−Tc, relevant 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 different power law for the Maki-Thompson contribution, δgMT∝(TcT−Tc)3/2. We suggest that peculiar nonmonotonous temperature dependence of the tunneling conductance may be probed via magnetotunnel experiments.

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