Room-temperature antiferromagnetic resonance in NaMnAs

TL;DR

This study demonstrates room-temperature antiferromagnetic resonance in NaMnAs, confirming theoretical predictions and providing insights into its magnetic properties and anisotropy.

Contribution

First experimental observation of room-temperature antiferromagnetic resonance in NaMnAs, validating theoretical models and estimating magnetic anisotropy.

Findings

Resonance at 7 meV persists up to room temperature.

Estimated single-ion anisotropy D ≈ 0.2 meV.

NaMnAs is an easy-axis antiferromagnet with a Néel vector along the tetragonal axis.

Abstract

We report on antiferromagnetic resonance experiments in bulk tetragonal NaMnAs -- a room-temperature antiferromagnetic semiconductor. Our results corroborate previous ab initio studies, which propose that NaMnAs is an easy-axis antiferromagnet with the N\'eel vector oriented along the tetragonal axis. At $ B = 0 $, we find a single antiferromagnetic resonance line at 7 meV and associate it with a doubly degenerate ($ k = 0 $) magnon mode. Its energy softens considerably with increasing $ T $, but remains clearly visible in the data up to room temperature. From the experimental data, we estimate the single-ion anisotropy of the Mn ions in NaMnAs to be $ D \approx 0.2 $ meV, a value that is relatively large compared to other manganese-based antiferromagnets.