What it is
Altermagnetism is a magnetic phase that bridges the properties of ferromagnetism and antiferromagnetism. The momentum-dependent spin splitting seen in such materials reflects their distinctive symmetry, which also sets the conditions for chiral magnons to appear: collective waves of spin that carry a definite handedness. The authors give direct experimental evidence for a chiral magnon in the altermagnetic candidate manganese telluride, revealed by circular-dichroism resonant inelastic x-ray scattering, which compares how the material scatters left- and right-handed circularly polarized light. They term the mode a chiral altermagnon. Its spin polarization varies with momentum in a way consistent with the g-wave altermagnetic symmetry of manganese telluride, and the polarization-resolved data support the existence of a discrete class of magnetic excitations, showing how altermagnetic order shapes spin dynamics.
Why it matters
Altermagnets were predicted to carry spin waves with a handedness fixed by their symmetry, and this measurement sees one directly. In the preprint, the dichroic signal changes sign across a nodal region where it vanishes, which is what the material's symmetry requires, and the magnon sits at an energy near 35 meV. Because altermagnets lack stray magnetic fields, the authors argue they suit compact, interference-free devices, and say the work paves the way for spin-based applications built on chiral altermagnons.
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Filed underAdvanced Condensed Matter Physics, Magnetic properties of thin films, Topological Materials and Phenomena
