Antiferromagnetic Resonance in MnF2

Abstract

Measurements of the antiferromagnetic resonance frequency, $\nu \mathrm{}\left(T\right)\mathrm{}$, were made on single-crystal slabs of Mn${\mathrm{F}}_2$ in the frequency range 96 to 247.2 kMc/sec and at temperatures, $T$, ranging from 4.2°K to 64°K ($T_N=67.7\mathrm{}°$K). The results are in general agreement with the resonance relations derived for antiferromagnetic materials by Nagamiya, Keffer, and Kittel, and others. At low temperatures, values of $\frac{\nu \mathrm{}\left(T\right)\mathrm{}}{\nu \mathrm{}\left(0\right)\mathrm{}}$ and $\nu \mathrm{}\left(0\right)\mathrm{}$ are consistent with spin-wave method calculations of the sublattice magnetization and of the value and temperature dependence of the anisotropy energy. This agreement indicates almost complete correlation of adjacent electron spins in the low-temperature range as predicted from spin-wave theory.