We have investigated the bound state of the exciton-magnon transition corresponding to the ${}_{}{}^6{}_{}{}^{}$${\mathit{A}}_{1\mathit{g}}$${\to }^4$${\mathit{A}}_{1\mathit{g}}$${,}^4$${\mathit{E}}_{\mathit{g}}$ transition in ${\mathrm{MnF}}_2$ under high magnetic fields. When an external magnetic field was applied along the c axis, this bound state changed dramatically at the spin-flop transition. From the analysis of the field dependence of the bound state, the exciton-magnon interaction responsible for the appearance of the bound state could be elucidated.

• Received 21 September 1992

DOI:https://doi.org/10.1103/PhysRevB.47.15086