ArXiv · 2025
Thomas J. Hicken (PSI Center for Neutron and Muon Sciences, Villigen, Switzerland), Klára Uhlířová (Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic), Helena Reichlová (Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic), Ondrej Caha (Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czechia), Vincent C. Morano (PSI Center for Neutron and Muon Sciences, Villigen, Switzerland), Oliver Amin (School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom), Alfred Dal Din (School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom), J. Hugo Dil (PSI Center for Photon Science, Villigen, Switzerland, Institut de Physique, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland), Marek Duchan (Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czechia), Dominik Kriegner (Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic), Hubertus Luetkens (PSI Center for Neutron and Muon Sciences, Villigen, Switzerland), Zeno Maesen (PSI Center for Neutron and Muon Sciences, Villigen, Switzerland), Jan Martinek (Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic), Zaher Salman (PSI Center for Neutron and Muon Sciences, Villigen, Switzerland), Peter Wadley (School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom), Oksana Zaharko (PSI Center for Neutron and Muon Sciences, Villigen, Switzerland), Juraj Krempaský (PSI Center for Photon Science, Villigen, Switzerland), Jonas A. Krieger (PSI Center for Neutron and Muon Sciences, Villigen, Switzerland)
Altermagnets are novel magnetic systems that possess a spin-polarized electronic band structure without a net magnetic moment, making them promising for device applications. Hexagonal MnTe, a prototypical altermagnet, arguably exhibits the most properties consistent with theoretical predictions, including an anomalous Hall effect despite a vanishing net magnetization, and altermagnetinduced electronic band splitting. However, fundamental questions remain, including why some effects only appear significantly below the magnetic ordering temperature. Here, we resolve this discrepancy by revealing a reorientation of the Néel vector in single-crystalline MnTe. The Néel vector points 30° from the a-axis at low T, before aligning directly with the a-axis around T≃ 260 K. We attribute this to single-ion anisotropy, which depends on temperature-dependent lattice parameters. We obtained these results using muon-spin spectroscopy, magnetization measurements, and X-ray diffraction; we show that the findings are consistent with neutron diffraction. Manipulating this effect, for example through strain, could unlock sensitive electronic detection schemes for external stimuli, paving the way for functional altermagnetic devices.
