Signature of a Z_2 vortex in the dynamical correlations of the triangular-lattice Heisenberg antiferromagnet

TL;DR

This study uses simulations and analytical methods to identify a distinctive central peak in the dynamical spin structure factor as evidence of Z_2-vortex excitations and a topological transition in the triangular-lattice Heisenberg antiferromagnet.

Contribution

It demonstrates that dynamical spin correlations can reveal Z_2-vortex signatures, providing a new way to detect topological transitions in magnetic systems.

Findings

Dynamical spin structure factor shows a central peak at the Z_2-vortex transition.

The central peak serves as a fingerprint of Z_2-vortex excitations.

The study links dynamical correlations to topological transitions in the model.

Abstract

Dynamical properties of the classical Heisenberg antiferromagnet on the triangular lattice are investigated by means of a spin-dynamics simulation and an analytical calculation. While the model was suggested to exhibit a topological transition driven by the Z_2-vortex binding-unbinding, weakness of the associated thermodynamic singularity has made it difficult to observe the evidence of the Z_2 vortex experimentally so far, only some indirect support. Here, we show that the signature of the Z_2-vortex excitation and the vortex-induced topological transition can be captured from the dynamical spin correlations. In particular, the dynamical spin structure factor exhibits a characteristic central peak around the Z_2-vortex transition, and this central peak will be a fingerprint of the Z_2-vortex excitation.