Magnetic phase diagrams of classical triangular and kagome antiferromagnets

TL;DR

This paper explores how geometrical frustration influences the magnetic phase diagrams of classical Heisenberg antiferromagnets on triangular and kagome lattices, revealing distinct thermal fluctuation effects and phase transitions.

Contribution

It provides large-scale Monte Carlo simulations of the phase diagrams, highlighting the inability of thermal fluctuations to fully lift degeneracy in kagome antiferromagnets and identifying specific phase transitions.

Findings

Thermal fluctuations do not fully lift degeneracy in kagome antiferromagnets.

A Kosterlitz-Thouless transition to a spin-nematic phase occurs at low fields.

Distinct temperature scales of order by disorder effect are observed in kagome antiferromagnets.

Abstract

We investigate the effect of geometrical frustration on the $H$--$T$ phase diagrams of the classical Heisenberg antiferromagnets on triangular and kagome lattices. The phase diagrams for the two models are obtained from large scale Monte Carlo simulations. For the kagome antiferromagnet thermal fluctuations are unable to lift completely degeneracy and stabilize translationally disordered multipolar phases. We find a substantial difference in the temperature scales of the order by disorder effect related to different degeneracy of the low- and the high-field classical ground states in the kagome antiferromagnet. In the low-field regime, the Kosterlitz-Thouless transition into a spin-nematic phase is produced by unbinding of half-quantum vortices.