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arXiv:1911.02932 · Physical review. B./Physical review. B

Helical spin liquid in a triangular XXZ magnet from Chern-Simons theory

Tigran Sedrakyan, Roderich Moessner, Alex Kamenev

Published Jul 20, 2020• 12 citations
arXivHTMLPDF

Abstract

We propose a finite-temperature phase diagram for the two-dimensional spin-$1/2$ ${J}_{1}\ensuremath{-}{J}_{2}$ XXZ antiferromagnet on a triangular lattice. Our analysis, based on a composite fermion representation, yields several phases. This includes a zero-temperature helical spin liquid with $N=6$ anisotropic Dirac cones, and with nonzero vector chirality implying a broken ${\mathbb{Z}}_{2}$ symmetry. It is terminated at $T=0$ by a continuous quantum phase transition to a ${120}^{\ensuremath{\circ}}$ ordered state around ${J}_{2}/{J}_{1}\ensuremath{\approx}0.089$ in the XX limit; these phases share a double degeneracy, which persists to finite $T$ above the helical spin liquid. By contrast, at ${J}_{2}/{J}_{1}\ensuremath{\simeq}0.116$, the transition into a stripe phase appears as first order. We further discuss experimental and numerical consequences of the helical order and the anisotropic nature of the Dirac dispersion.

DOI
10.1103/physrevb.102.024430

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