Tricritical behavior of the frustrated XY antiferromagnet

TL;DR

This study uses Monte Carlo simulations to analyze the critical behavior of the XY antiferromagnet on a triangular lattice, revealing mean-field tricritical behavior and decoupled chiral transition, clarifying long-standing debates.

Contribution

It provides the first strong numerical evidence for mean-field tricritical behavior in frustrated XY antiferromagnets, resolving previous controversies.

Findings

Spin-order transition exhibits mean-field tricritical behavior.

Chiral-order transition occurs at the same temperature but is decoupled.

Results clarify criticality in frustrated planar systems.

Abstract

Extensive histogram Monte-Carlo simulations of the XY antiferromagnet on a stacked triangular lattice reveal exponent estimates which strongly favor a scenario of mean-field tricritical behavior for the spin-order transition. The corresponding chiral-order transition occurs at the same temperature but appears to be decoupled from the spin-order. These results are relevant to a wide class of frustrated systems with planar-type order and serve to resolve a long-standing controversy regarding their criticality.