Sine-Gordon description of Beresinskii-Kosterlitz-Thouless physics at finite magnetic field

TL;DR

This paper uses a sine-Gordon field-theoretical model to analyze vortex behavior and magnetization in two-dimensional superconductors under finite magnetic fields, highlighting non-linear effects near the BKT transition.

Contribution

It introduces a sine-Gordon based framework to describe BKT physics at finite magnetic fields, providing new insights into vortex dynamics and magnetization.

Findings

Field-induced magnetization can be straightforwardly defined.

Non-linear effects persist at low fields above the transition.

Correlation length diverges rapidly near the BKT transition.

Abstract

The Beresinskii-Kosterlitz-Thouless (BKT) physics of vortices in two-dimensional superconductors at finite magnetic field is investigated by means of a field-theoretical approach based on the sine-Gordon model. This description leads to a straightforward definition of the field-induced magnetization and shows that the persistence of non-linear effects at low fields above the transition is a typical signature of the fast divergence of the correlation length within the BKT theory.