High-Field Antiferromagnetic Resonance in MnF2Using Pulsed Fields and Millimeter Wavelengths

Abstract

Preliminary observations of the high-field antiferromagnetic resonance mode in Mn${\mathrm{F}}_2$ from 4.2°K up to $T_N$ are presented. The experiments, which employ pulsed magnetic fields and relatively low frequencies (4 and 8 millimeter wavelengths), are briefly described. The absolute value and general temperature dependence of ${\left(2\mathrm{}{H}_E{H}_A\right)}^{\frac{1}{2}}$ are in close agreement with estimates made earlier by Keffer and recent high-frequency measurements by Johnson and Nethercot near $T_N$. The results demonstrate the general validity of the molecular-field approximation of antiferromagnetic resonance. Qualitative features of the resonance absorption and upper bounds of line widths are also presented.