Spontaneous Anomalous Hall Effect at Room Temperature in Antiferromagnetic Material NbMnAs

Recent studies have shown that certain antiferromagnetic (AFM) materials with the same symmetry breaking as ferromagnets can generate sufficiently large ferromagnetic (FM) responses. Here, we report that the new AFM material NbMnAs exhibits a large anomalous Hall effect (AHE) at zero field and at room temperature, despite having only a small net magnetization. A polycrystalline sample of NbMnAs, likely close to stoichiometric composition, exhibited an AFM state with a small spontaneous magnetization of approximately $6 \times 10^{-3} μ_{\rm B}$/Mn and the AHE below $T_{\rm N}=354\,{\rm K}$. In contrast, single crystals of NbMnAs obtained by a flux method exhibited a deficiency at the As site, {which resulted} in a decrease in $T_{\rm N}$ and an increase in spontaneous magnetization. Although improvement of the single-crystal growth is still required, our study reveals that NbMnAs is a novel material capable of exhibiting significant FM responses derived from antiferromagnetism at room temperature.