Coulomb Gap and Correlated Vortex Pinning in Superconductors

TL;DR

This paper investigates the Coulomb gap and vortex pinning in superconductors, showing how long-range interactions influence the density of states and flux line transport in the Bose glass phase.

Contribution

It provides the first calculation of the Coulomb gap in vortex systems using experimental pinning data, revealing the impact of interactions on flux transport.

Findings

A wide Coulomb gap with exponent s ≈ 1.2 was observed.

Long-range vortex interactions significantly reduce flux transport.

Effective Mott exponent increased from 1/3 to approximately 0.5.

Abstract

The positions of columnar pins and magnetic flux lines determined from a decoration experiment on BSCCO were used to calculate the single--particle density of states at low temperatures in the Bose glass phase. A wide Coulomb gap is found, with gap exponent $s \approx 1.2$, as a result of the long--range interaction between the vortices. As a consequence, the variable--range hopping transport of flux lines is considerably reduced with respect to the non--interacting case, the effective Mott exponent being enhanced from $p_0 = 1/3$ to $p_{\rm eff} \approx 0.5$ for this specific experiment.