Critical States in Disordered Superconducting Films

TL;DR

This paper explores how disordered superconducting films under pair-breaking perturbations can develop a glass-like phase with multifractal correlations, potentially altering the nature of quantum phase transitions.

Contribution

It proposes that a glass-like phase with multifractal correlations can preempt the superconducting transition in disordered films under magnetic fields.

Findings

Mesoscopic fluctuations significantly affect pairing susceptibility.

A glass-like phase may form before the superconducting transition.

This behavior could be common in disordered quantum critical systems.

Abstract

When subject to a pair-breaking perturbation, the pairing susceptibility of a disordered superconductor exhibits substantial long-ranged mesoscopic fluctuations. Focusing on a thin film subject to a parallel magnetic field, it is proposed that the quantum phase transition to the bulk superconducting condensate may be preempted by the formation of a glass-like phase with multi-fractal correlations of a complex order parameter. Although not universal, we argue that such behavior may be a common feature of quantum critical phenomena in disordered environments.