Theory of the algebraic vortex liquid in an anisotropic spin-1/2 triangular antiferromagnet

TL;DR

This paper introduces the algebraic vortex liquid as a novel critical spin liquid state in anisotropic spin-1/2 triangular antiferromagnets, characterized by non-compact QED3 and emergent SU(4) symmetry, and explores its phases and excitations.

Contribution

It develops a dual vortex fermionization approach to characterize a new algebraic vortex liquid state in anisotropic triangular antiferromagnets, linking it to known phases and explaining recent spectral features.

Findings

Identification of the algebraic vortex liquid as a distinct critical spin liquid.

Description of descendant phases including Kalmeyer-Laughlin spin liquid and ordered states.

Explanation of roton minima in excitation spectrum within this framework.

Abstract

We explore spin-1/2 triangular antiferromagnets with both easy-plane and lattice exchange anisotropies by employing a dual vortex mapping followed by a fermionization of the vortices. Over a broad range of exchange anisotropy, this approach leads naturally to a ``critical'' spin liquid--the algebraic vortex liquid--which appears to be distinct from other known spin liquids. We present a detailed characterization of this state, which is described in terms of non-compact QED3 with an emergent SU(4) symmetry. Descendant phases of the algebraic vortex liquid are also explored, which include the Kalmeyer-Laughlin spin liquid, a variety of magnetically ordered states such as the well known coplanar spiral state, and supersolids. In the range of exchange anisotropy where the ``square lattice'' Neel ground state arises, we demonstrate that anomalous ``roton'' minima in the excitation spectrum recently reported in series expansions can be accounted for within our approach.