Dissipation-Driven Breakdown of Universality in Two-Dimensional Superconductors

TL;DR

This paper investigates how gapless dissipative environments affect the superconductor-insulator transition in 2D systems, revealing a transition from universal to non-universal critical behavior and proposing a new universality class.

Contribution

It develops a series expansion for a 2+1D XY model coupled to a heat bath, explicitly conserving topological excitations, and identifies a dissipation-driven change in universality class.

Findings

Transition from universal to non-universal scaling with increased dissipation

Derivation of the zero temperature phase diagram

Identification of a new universality class

Abstract

The influence of gapless dissipative degrees of freedom on the superconductor-insulator transition in two dimensions is investigated. We develop a series expansion for the free energy of a (2+1)-dimensional XY model coupled to a bosonic heat bath that can be approximately summed to all orders. The calculation explicitly conserves topological excitations. We derive the zero temperature phase diagram and the free energy critical exponent, and find a transition from universal to non-universal scaling behavior as the coupling to the dissipative environment is increased, implying the existence of a new universality class.