Magnon crystallization in the kagome lattice antiferromagnet

TL;DR

This paper provides numerical evidence for magnon crystallization in a highly frustrated kagome antiferromagnet, revealing a phase transition driven by localized magnons and offering insights into experimental observation conditions.

Contribution

It introduces a loop-gas model for localized magnons and maps out the phase diagram of magnon crystallization in the kagome lattice.

Findings

Magnon crystallization occurs below the saturation field at finite temperatures.

A phase diagram for the transition is provided, indicating observable conditions.

The phenomenon is linked to flat-band multi-magnon states breaking translational symmetry.

Abstract

We present numerical evidence for the crystallization of magnons below the saturation field at non-zero temperatures for the highly frustrated spin-half kagome Heisenberg antiferromagnet. This phenomenon can be traced back to the existence of independent localized magnons or equivalently flat-band multi-magnon states. We present a loop-gas description of these localized magnons and a phase diagram of this transition, thus providing information for which magnetic fields and temperatures magnon crystallization can be observed experimentally. The emergence of a finite-temperature continuous transition to a magnon-crystal is expected to be generic for spin models in dimension $D>1$ where flat-band multi-magnon ground states break translational symmetry.