# Broadening of the Berezinskii-Kosterlitz-Thouless transition by correlated disorder

## TL;DR

This paper investigates how correlated disorder in two-dimensional superconductors broadens the Berezinskii-Kosterlitz-Thouless transition, causing a smearing of the superfluid-density jump and aligning theory with experimental findings.

## Contribution

It reveals that disorder-induced granularity alters vortex nucleation, broadening the BKT transition in a way not previously understood.

## Key findings

- Superfluid-density jump is smeared by correlated disorder.
- Disorder modifies vortex-antivortex nucleation mechanisms.
- Results agree with experimental observations.

## Abstract

The Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional superconductors is usually expected to be protected against disorder. However, its typical signatures in real system, like e.g. the superfluid-density jump, are often at odd with this expectation. Here we show that the disorder-induced granularity of the superconducting state modifies the nucleation mechanism for vortex-antivortex pairs. This leads to a considerable smearing of the universal superfluid-density jump as compared to the paradigmatic clean case, in agreement with experimental observations.