Altermagnets are a novel type of magnetic system that has a spin-polarised electric band structure in the absence of a net magnetic moment, leading to exciting prospects in potential device applications. Hexagonal MnTe, a prototypical altermagnet, has arguably shown the most properties consistent with theoretical predictions, including an anomalous Hall effect despite no net magnetisation, and strong altermagnet-induced spin splitting in the electronic band structure. Here we present muon-spin spectroscopy measurements of a single crystal of MnTe. Below room temperature we observe pronounced anomalies in the muon-spin depolarisation, as well as the onset of a second, non-proportional internal field in the absence of an applied field. These findings point to a change in the magnetic structure around T≃250 K, which coincides with other changes in reported properties, such as transport.
@article{arxiv.2507.14710,
title = {Anomalous temperature dependence of local magnetic fields in altermagnetic MnTe},
author = {Thomas J. Hicken and Oliver Amin and Alfred Dal Din and J. Hugo Dil and Dominik Kriegner and Hubertus Luetkens and Helena Reichlová and Zaher Salman and Klára Uhlířová and Peter Wadley and Juraj Krempaský and Jonas A. Krieger},
journal= {arXiv preprint arXiv:2507.14710},
year = {2025}
}