Dual Order Parameter for the Nodal Liquid

TL;DR

This paper explores vortex condensation in 2D electronic systems, revealing how different flux vortices lead to various insulating phases, including the nodal liquid with spin-charge separation.

Contribution

It extends the vortex-condensation framework from 1D and bosonic systems to 2D electronic systems, highlighting the role of flux hc/2e and hc/e vortices in different insulating states.

Findings

Flux hc/2e vortices lead to spin-charge confinement.

Flux hc/e vortices enable spin-charge separation.

Identification of a 2D Mott insulator with spin-charge separation.

Abstract

The guiding conception of vortex-condensation-driven Mott insulating behavior is central to the theory of the nodal liquid. We amplify our earlier description of this idea and show how vortex condensation in 2D electronic systems is a natural extension of 1D Mott insulating and 2D bosonic Mott insulating behavior. For vortices in an underlying superconducting pair field, there is an important distinction between the condensation of flux hc/2e and flux hc/e vortices. The former case leads to spin-charge confinement, exemplified by the band insulator and the charge-density-wave. In the latter case, spin and charge are liberated leading directly to a 2D Mott insulator exhibiting *spin-charge separation*. Possible upshots include not only the nodal liquid, but also a novel undoped antiferromagnetic insulating phase with gapped excitations exhibiting spin-charge separation.