Confinement transition to density wave order in metallic doped spin liquids

TL;DR

This paper develops a theory for confinement transitions in metallic doped spin liquids, showing how density wave order can emerge from topological excitations, with relevance to cuprate superconductor experiments.

Contribution

It extends confinement transition theory to fractionalized Fermi liquids, incorporating effects of Fermi surfaces and proposing a mechanism for incommensurate density wave states.

Findings

Density wave states can result from vison condensation in FL* states.

Fermi surfaces introduce additional frustrating interactions.

The theory explains incommensurate density waves observed in cuprates.

Abstract

Insulating quantum spin liquids can undergo a confinement transition to a valence bond solid state via the condensation of topological excitations of the associated gauge theory. We extend the theory of such transitions to fractionalized Fermi liquids (FL*): these are metallic doped spin liquids in which the Fermi surfaces only have gauge neutral quasiparticles. Using insights from a duality transform on a doped quantum dimer model for the U(1)-FL* state, we show that projective symmetry group of the theory of the topological excitations remains unmodified, but the Fermi surfaces can lead to additional frustrating interactions. We propose a theory for the confinement transition of $\mathbb{Z}_2$-FL* states via the condensation of visons. A variety of confining, incommensurate density wave states are possible, including some that are similar to the incommensurate $d$-form factor density wave order observed in several recent experiments on the cuprate superconductors.