Crossover and scaling in a two-dimensional field-tuned superconductor

TL;DR

This paper proposes that the observed superconductor-metal transition in a 2D system is a crossover to an inhomogeneous weak superconductor state, with the true transition being a superconductor-insulator transition described by a diluted XY model.

Contribution

It introduces a new interpretation of the superconductor-metal transition as a crossover and suggests the superconductor-insulator transition is governed by a diluted XY model.

Findings

The apparent first order transition is a crossover, not a true phase transition.

The true transition is a superconductor-insulator transition in a diluted XY model.

Finite temperature resistivity scaling can be explained within this framework.

Abstract

Using an analysis similar to that of Imry and Wortis, it is shown that the apparent first order superconductor to metal transition, which has been claimed to exist at low values of the magnetic field in a two-dimensional field-tuned system at zero temperature,can be consistentlyinterpreted as a sharp crossover from a strong superconductor to an inhomogeneous state, which is a weak superconductor. The true zero-temperature superconductor to insulator transition within the inhomogenous state is conjectured to be that of randomly diluted XY model. An explaination of the observed finite temperature approximate scaling of resistivity close to the critical point is speculated within this model.