Monte Carlo Study of the Anisotropic Heisenberg Antiferromagnet on the Triangular Lattice

TL;DR

This paper uses Monte Carlo simulations to investigate phase transitions in an anisotropic Heisenberg antiferromagnet on a triangular lattice, revealing two types of vortex-driven transitions.

Contribution

It provides the first detailed Monte Carlo analysis of vortex and spin wave excitations in this specific model, identifying two distinct Kosterlitz-Thouless transitions.

Findings

Identification of two separate vortex-driven phase transitions.

Quantitative analysis of spin stiffness and vorticity modulus.

Evidence supporting the existence of two Kosterlitz-Thouless transitions.

Abstract

We report a Monte Carlo study of the classical antiferromagnetic Heisenberg model with easy axis anisotropy on the triangular lattice. Both the free energy cost for long wavelength spin waves as well as for the formation of free vortices are obtained from the spin stiffness and vorticity modulus respectively. Evidence for two distinct Kosterlitz-Thouless types of defect-mediated phase transitions at finite temperatures is presented.