Anisotropy-induced ordering in the quantum J1-J2 antiferromagnet

TL;DR

This paper investigates how spin anisotropies influence the phase diagram of a frustrated quantum antiferromagnet, revealing stabilization of XY- and Ising-like orders and a limited spin-liquid region.

Contribution

It provides a comprehensive analysis of anisotropy effects on the J1-J2 model using multiple methods, highlighting new phase stability and transition phenomena.

Findings

Anisotropic frustration stabilizes XY- and Ising-like phases.

Spin-liquid phase is confined to a small region.

First-order transitions and reentrance phenomena are observed.

Abstract

We study the effect of spin anisotropies on a frustrated quantum antiferromagnet using the J_1-J_2^{XXZ} model on the square lattice. The T=0 and finite-T phase diagrams of this model are obtained utilizing spin-wave theory, exact diagonalization, and quantum Monte Carlo. We find that anisotropic frustration tends to stabilize XY- and Ising-like ordered phases, while the disordered spin-liquid phase is restricted to a small region of the phase diagram. The ordered phases are separated by first-order transitions and exhibit a non-trivial reentrance phenomenon.