First order transition induced by topological defects in the O(3) principal chiral model

TL;DR

This study uses Monte Carlo simulations to demonstrate that topological defects induce a first order phase transition in the O(3) principal chiral model and related frustrated antiferromagnetic systems.

Contribution

It provides the first evidence that topological defects can induce first order transitions in the O(3) principal chiral model and similar systems.

Findings

First order transition observed in the lattice O(3) principal chiral model.

Topological defects qualitatively linked to the transition.

Similar first order transition found in a frustrated antiferromagnet model.

Abstract

Using Monte Carlo simulations, we study thermal and critical properties of two systems, in which domain walls and so-called $Z_2$-vortices as topological defects are presented. The main model is a lattice version of the $O(3)$ principal chiral model. We find a first order transition and give qualitative arguments that the first order is induced by topological defects. We also consider the model of frustrated antiferromagnet on a square lattice with the additional exchange interaction between spins of the third range order. This model belongs to the same symmetry class. In this model, a transition is of first order too.