Strong thermal fluctuations in cuprate superconductors in magnetic field above Tc

TL;DR

This paper presents a self-consistent Ginzburg-Landau-Lawrence-Doniach model calculation that accurately describes fluctuation diamagnetism in cuprate superconductors around Tc, surpassing simple gaussian theories.

Contribution

It introduces a comprehensive Landau level approach to model magnetization in layered high-Tc superconductors, aligning well with experimental data.

Findings

Gaussian fluctuation theory overestimates diamagnetism for strong fluctuations

Intersection point of magnetization curves occurs where lowest Landau level dominates

Model captures both vortex liquid below Tc and normal state above Tc

Abstract

Recent measurements of fluctuation diamagnetism in high temperature superconductors show distinct features above and below Tc, which can not be explained by simple gaussian fluctuation theory. Self consistent calculation of magnetization in layered high temperature superconductors, based on the Ginzburg-Landau-Lawrence-Doniach model and including all Landau levels is presented. The results agree well with the experimental data in wide region around Tc, including both the vortex liquid below Tc and the normal state above Tc. The gaussian fluctuation theory significantly over estimates the diamagnetism for strong fluctuations. It is demonstrated that the intersection point of magnetization curves appears in the region where the lowest Landau level contribution dominates.