  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.
