Destruction of superconductivity in disordered materials : a dimensional crossover

TL;DR

This paper investigates how disorder and dimensionality affect the superconductor-to-insulator transition in amorphous NbSi thin films, revealing a crossover from 2D to 3D behavior influenced by composition and thickness.

Contribution

It provides a detailed phase diagram showing the critical thickness dependence on niobium composition, linking 2D superconductor-insulator transition to 3D superconductor-metal transition.

Findings

Critical thickness increases as niobium composition decreases.

Phase diagram connects 2D superconductor-insulator transition with 3D superconductor-metal transition.

Superconductivity destruction depends on disorder and dimensional crossover.

Abstract

The disorder-induced Superconductor-to-Insulator Transition in amorphous Nb$_{x}$Si$_{1-x}$ two-dimensional thin films is studied for different niobium compositions $x$ through a variation of the sample thickness $d$. We show that the critical thickness $d_c$, separating a superconducting regime from an insulating one, increases strongly with diminishing $x$, thus attaining values of over 100 {\AA}. The corresponding phase diagram in the $(d, x)$ plane is inferred and related to the three-dimensional situation. The two-dimensional Superconductor-to-Insulator Transition well connects with the three-dimensional Superconductor-to-Metal Transition.