# Magnon-Mediated Indirect Exciton Condensation through Antiferromagnetic Insulators

## TL;DR

This paper proposes a new method to enhance indirect exciton condensation temperature by using magnon-mediated interactions in a trilayer system with antiferromagnetic insulators, potentially increasing the operational temperature range.

## Contribution

It introduces a theoretical model for magnon-mediated exciton interactions in antiferromagnetic insulators, showing how interface engineering can control the interaction's nature and estimate the critical temperature for condensation.

## Key findings

- Magnon-mediated interaction can be tuned to be attractive or repulsive by adjusting the insulator thickness.
- The critical temperature for exciton condensation can reach around 7 K with realistic parameters.
- Anisotropy and exchange interactions significantly influence the condensation temperature.

## Abstract

Electrons and holes residing on the opposing sides of an insulating barrier and experiencing an attractive Coulomb interaction can spontaneously form a coherent state known as an indirect exciton condensate. We study a trilayer system where the barrier is an antiferromagnetic insulator. The electrons and holes here additionally interact via interfacial coupling to the antiferromagnetic magnons. We show that by employing magnetically uncompensated interfaces, we can design the magnon-mediated interaction to be attractive or repulsive by varying the thickness of the antiferromagnetic insulator by a single atomic layer. We derive an analytical expression for the critical temperature $T_c$ of the indirect exciton condensation. Within our model, anisotropy is found to be crucial for achieving a finite $T_c$, which increases with the strength of the exchange interaction in the antiferromagnetic bulk. For realistic material parameters, we estimate $T_c$ to be around 7 K, the same order of magnitude as the current experimentally achievable exciton condensation where the attraction is solely due to the Coulomb interaction. The magnon-mediated interaction is expected to cooperate with the Coulomb interaction for condensation of indirect excitons, thereby providing a means to significantly increase the exciton condensation temperature range.