Phase fluctuations in finite thickness disordered superconducting thin films

TL;DR

This paper theoretically investigates phase fluctuations in layered disordered superconducting thin films, revealing how the system's phase stiffness and critical temperature depend on thickness, aligning with experimental observations of superconductor-insulator transitions.

Contribution

It introduces a model showing the effective phase stiffness scales with film thickness, explaining the inverse relationship between critical temperature and thickness in disordered superconducting films.

Findings

Effective phase stiffness is proportional to the number of layers.

Critical temperature T_c scales inversely with film thickness.

Results agree with experimental superconductor-insulator transition data.

Abstract

Phase fluctuations in finite thickness layered superconducting films are studied theoretically. The model consists of a set of layers, coupled to each other via a gradient-like term in the phase-only action. It is shown that the effective phase stiffness of the whole system is proportional to its thickness (i.e. the number of individual layers). This result leads to a superconductor-insulator transition and an inverse dependence of $T_c$ on thickness,$T_c\sim d^{-1}$, both in accord with the experimental findings. The relevance to disordered thin films is discussed.