Interplay between spatial anisotropy and further exchange interactions in the triangular Heisenberg model

TL;DR

This study explores how spatial anisotropy and additional exchange interactions influence the phase diagram of the spin-1/2 Heisenberg antiferromagnet on a triangular lattice, revealing a complex interplay that favors spin liquid states.

Contribution

It introduces a Schwinger boson approach with Gaussian fluctuations to analyze the phase diagram, highlighting the effects of anisotropy on magnetic order and spin liquid regions.

Findings

Reduction of long-range magnetic orders due to anisotropy

Emergence of short-range order and spin liquid phases

Fragility of spiral orders near the isotropic point

Abstract

We investigate the interplay between spatial anisotropy and further exchange interactions in the spin-$\frac{1}{2}$ Heisenberg antiferromagnetic model on a triangular lattice. We use the Schwinger boson theory by including Gaussian fluctuations above the mean-field approach. The phase diagram exhibits a strong reduction of the long range collinear and incommensurate spirals regions with respect to the mean-field ones. This reduction is accompanied by the emergence of its short range order counterparts, leaving an ample room for $0$-flux and nematic spin liquid regions. Remarkably, within the neighborhood of the spatially isotropic line, there is a range where the spirals are so fragile that only the commensurate $120^{\circ}$ N\'eel ones survive. The good agreement with recent variational Monte Carlo predictions gives support to the rich phase diagram induced by spatial anisotropy.