Competing Order in the Mixed State of High Temperature Superconductors

TL;DR

This paper investigates the low temperature behavior of layered high-temperature superconductors near a quantum critical point, revealing an avoided critical point and a quasi-1D regime with localized competing order around vortices.

Contribution

It introduces the concept of an avoided critical point and describes a quasi-1D regime where competing order is confined to vortex halos in high-temperature superconductors.

Findings

Existence of an avoided critical point at zero temperature.

Competing order forms localized halos around vortex cores.

Weak interactions between vortices in the quasi-1D regime.

Abstract

We examine the low temperature behavior of the mixed state of a layered superconductor in the vicinity of a quantum critical point separating a pure superconducting phase from a phase in which a competing order coexists with superconductivity. At zero temperature, we find that there is an avoided critical point in the sense that the phase boundary in the limit $B\to 0$ does not connect to the B=0 critical point. Consequently, there exists a quasi-1D regime of the phase diagram, in which the competing order is largely confined to 1D ``halos'' about each vortex core, and in which interactions between neighboring vortices, although relevant at low temperature, are relatively weak.