Probing inhomogeneities in type II superconductors by means of thermal fluctuations, magnetic fields and isotope effects

TL;DR

This paper investigates how inhomogeneities in type II superconductors affect their thermodynamic properties, revealing finite size effects due to nanoscale domains and the influence of lattice distortions on transition temperature and superfluidity.

Contribution

It demonstrates that finite size effects from nanoscale domains significantly impact the thermodynamic behavior of type II superconductors, linking lattice distortions to superconducting properties.

Findings

Finite size effects are evident in specific heat and penetration depth data.

Transition temperature and superfluidity increase as domain size decreases.

Local lattice distortions play a crucial role in superconducting behavior.

Abstract

Type II superconductors, consisting of superconducting domains embedded in a normal or insulating matrix, undergo a rounded phase transition. Indeed, the correlation length cannot grow beyond the spatial extent of the domains. Accordingly, the thermodynamic properties will exhibit a finite size effect. It is shown that the specific heat and penetration depth data of a variety of type II superconductors, including cuprates, exhibit the characteristic properties of a finite size effect, arising from domains with nanoscale extent. The finite size scaling analysis reveals essential features of the mechanism. Transition temperature and superfluidity increase with reduced domain size. The combined finite size and isotope effects uncover the relevance of local lattice distortions