Superconductor/Insulator Transition in the Striped Phase

TL;DR

This paper investigates the quantum phase transition of a charged stripe from an insulator to a superconductor at zero temperature, driven by the ratio of hopping amplitude to string tension, revealing a Kosterlitz-Thouless transition.

Contribution

It models the stripe dynamics as a quantum string and maps the transition to a Josephson junction chain, identifying the critical point for the insulator-superconductor transition.

Findings

At low hopping, the system is insulating due to pinning.

High hopping leads to a superconducting kink-condensate state.

A Kosterlitz-Thouless transition occurs at a critical ratio of hopping to tension.

Abstract

We study the transversal dynamics of a charged stripe (quantum string) at $T = 0$ and show that its kink excitations play the role of current carriers. If the hopping amplitude $t$ is much smaller than the string tension $J$, the string is pinned and its ground state (GS) is insulating. At $t \gg J$, the string is depinned and the GS is a kink-condensate. By mapping the system onto a Josephson junction chain, we show that this state is superconducting. At $(t/J)_c = 2 / \pi^2 $ the kink/antikink pairs decouple and a Kosterlitz-Thouless like insulator-superconductor transition occurs.