Role of Anisotropy in the Critical-Point Anomaly in EPR Linewidth of MnF2

EPR linewidth measurements in Mn${\mathrm{F}}_2$ are reported near the Néel temperature $T_N$ as a function of orientation and temperature. The angular dependence of the temperature-dependent part of the linewidth for $T\lesssim T_N+10\mathrm{}°$K follows the curve ($1-\frac{1}{2}{sin}^2\theta$), in agreement with the prediction of a recent theory by Huber ($\theta =0\mathrm{}$ for magnetic field $\overrightarrow{\mathrm{H}}\parallel \overrightarrow{\mathrm{c}}$ axis). The observed breakdown of the Huber theory for $T>\mathrm{}{T}_N+10\mathrm{}°$K is briefly discussed.