# Controlling stability of Bose-Einstein condensation of interacting magnons in an antiferromagnet by an external magnetic field

## TL;DR

This paper investigates how external magnetic fields influence the stability of magnon Bose-Einstein condensation in antiferromagnets, highlighting the role of inter- and intraband interactions in stabilization.

## Contribution

It introduces a mechanism to control magnon BEC stability via magnetic fields, considering the effects of magnon interactions in a two-sublattice antiferromagnet.

## Key findings

- Without magnetic field, attractive interband interactions destabilize BEC.
- A sufficiently strong magnetic field stabilizes BEC by enhancing intraband interactions.
- First analysis of interaction effects on magnon BEC stability in antiferromagnets.

## Abstract

We propose a mechanism for destabilizing or stabilizing Bose-Einstein condensation (BEC) of interacting magnons in an antiferromagnet. We study how the interaction between magnons affects the magnon BEC in a two-sublattice antiferromagnet without and with an external magnetic field. We show that in the absence of the magnetic field the magnon BEC is destabilized by the attractive interband interaction, which is larger than the repulsive intraband interaction. We also show that in the presence of the magnetic field the magnon BEC is stabilized only if the magnetic field is large enough to make the intraband interaction larger than the interband interaction. Our results provide the first step for understanding the interaction effects on the magnon BEC in antiferromagnets and may open interaction physics of multicomponent BEC of magnons in magnets.