Disorder Influences the Quantum Critical Transport at a Superconductor to Insulator Transition

TL;DR

This study investigates how flux disorder affects the critical transport properties at the superconductor-insulator transition, revealing non-universal behavior of critical resistance with increasing disorder.

Contribution

It isolates flux disorder effects on quantum critical transport at the superconductor-insulator transition using patterned films with controlled disorder.

Findings

Flux disorder increases with magnetic field in patterned films.

Critical resistance at the transition grows with flux disorder, contradicting universality.

Flux matching effects limit the number of observed transitions.

Abstract

We isolated flux disorder effects on the transport at the critical point of the quantum magnetic field tuned Superconductor to Insulator transition (BSIT). The experiments employed films patterned into geometrically disordered hexagonal arrays. Spatial variations in the flux per unit cell, which grow in a perpendicular magnetic field, constitute flux disorder. The growth of flux disorder with magnetic field limited the number of BSITs exhibited by a single film due to flux matching effects. The critical metallic resistance at successive BSITs grew with flux disorder contrary to predictions of its universality. These results open the door for controlled studies of disorder effects on the universality class of an ubiquitous quantum phase transition.