New Universality Class at the Magnetic Field Tuned Superconductor-Insulator Transition?

TL;DR

This paper investigates the superconductor-insulator transition in ultrathin amorphous Bi films under magnetic fields, revealing a new critical exponent product that differs from previous studies, suggesting a potential new universality class.

Contribution

The study provides a finite size scaling analysis of ultrathin Bi films, identifying a critical exponent product vz=0.7, indicating a possible new universality class at the transition.

Findings

Critical exponent product vz=0.7 in Bi films

Discrepancy with previous experiments on InOx and MoGe

Discussion of possible reasons for differing exponents

Abstract

The superconductor-insulator transition in ultrathin films of amorphous Bi was tuned by an applied magnetic field. A finite size scaling analysis has been carried out to determine the critical exponent product vz=0.7 for five films of different thicknesses and normal state resistances. This result differs from the exponents found in previous experiments on InOx and MoGe films. We discuss several possible reasons for this disagreement.