Theory of the striped superconductor

TL;DR

This paper introduces the concept of a pair density wave (PDW), specifically a striped superconductor, as a new phase of matter that may explain anomalies in high-temperature superconductors like La$_{2-x}$ Ba$_x$CuO$_4$, supported by a microscopic model and theoretical analysis.

Contribution

It defines the PDW phase, presents a solvable microscopic model supporting it, and explores its coupling with other orders and sensitivity to disorder.

Findings

Supports a PDW ground state with strong electron interactions

Explains experimental anomalies in high-temperature superconductors

Analyzes coupling and disorder effects on the PDW state

Abstract

We define a distinct phase of matter, a "pair density wave" (PDW), in which the superconducting order parameter $\phi$ varies periodically as a function of position such that when averaged over the center of mass position, all components of $\phi$ vanish identically. Specifically, we study the simplest, unidirectional PDW, the "striped superconductor," which we argue may be at the heart of a number of spectacular experimental anomalies that have been observed in the failed high temperature superconductor, La$_{2-x}$ Ba$_x$CuO$_4$. We present a solvable microscopic model with strong electron-electron interactions which supports a PDW groundstate. We also discuss, at the level of Landau theory, the nature of the coupling between the PDW and other order parameters, and the origins and some consequences of the unusual sensitivity of this state to quenched disorder.