Observation of antiferromagnetic resonance in epitaxial films of MnF2.

Antiferromagnetic resonance has been observed in thin films for what we believe to be the first time. Epitaxial films of ${\mathrm{MnF}}_{2}$ on ${\mathrm{MgF}}_{2}$, ${\mathrm{ZnF}}_{2}$, and ${\mathrm{FeF}}_{2}$ substrates were used. The resonance positions were very close to, but slightly below, that extrapolated for the bottom of the spin-wave band in bulk ${\mathrm{MnF}}_{2}$. The linewidths ranged from 15 to 500 Oe, with the narrowest ones corresponding to films with the best degree of epitaxy as judged by texture camera photographs.