New Universality Class at the Superconductor--Insulator Transition

TL;DR

This paper introduces a new universality class at the superconductor-insulator transition characterized by non-universal conductivity and damping-dependent critical dynamics, based on a phase representation with local ohmic dissipation.

Contribution

It proposes a novel universality class arising from strong damping effects in the superconductor-insulator transition, with a new theoretical framework incorporating local ohmic dissipation.

Findings

Identification of a new universality class with non-universal conductivity.

Damping-dependent dynamical critical exponent.

Description of magnetic field-tuned transition mechanisms.

Abstract

We study dynamic properties of thin films near the superconductor - insulator transition. We formulate the problem in a phase representation. The key new feature of our model is the assumption of a {\it local} ohmic dissipative mechanism. Coarse graining leads to a Ginzburg-Landau description, with non-ohmic dynamics for the order parameter. For strong enough damping a new universality class is observed. It is characterized by a {\it non-universal} d.c. conductivity, and a damping dependent dynamical critical exponent. The formulation also provides a description of the magnetic field-tuned transition. Several microscopic mechanisms are proposed as the origin of the dissipation.