Plaid‐Like Spin Splitting and Chirality of Magnon Bands in Antiferromagnetic MnTe ₂

ABSTRACT Altermagnets constitute an emerging class of magnetic materials that combine compensated antiferromagnetic order with spin‐split excitations arising from crystalline symmetries. Despite strong theoretical interest, their experimental identification remains challenging. Here, we demonstrate that helicity‐ and angle‐resolved Raman scattering measurements reveal reduced rotational symmetries of magnons and a pronounced imbalance between left‐ and right‐circular polarization channels, indicating momentum‐dependent magnon handedness. First‐principles DFT+ calculations combined with linear spin‐wave theory uncover a characteristic plaid‐like spin‐splitting structure in momentum space. The resulting magnon spin textures are dictated by the unconventional sublattice symmetries of and closely emulate those of altermagnetic electronic bands. Our work provides evidence of chiral spin‐wave excitations unique to this non‐coplanar antiferromagnet.