Exciton-Magnon Interaction in Magnetic Insulators

The one-exciton, one-magnon system is treated for a suitable antiferromagnetic insulator, Mn${\mathrm{F}}_2$. Zone-edge excitons and magnons are found to interact quite strongly. Bound states are found to exist under favorable circumstances. The line shapes of magnon sidebands of excitonic transitions are modified. Expressions are given for the exciton-magnon coupling constants in terms of the parameters describing interionic exchange.