Persistence of g-wave magnon structure across the Morin transition

Determine whether the angular dependence of the magnon splitting Δ(θ) and its nodal structure persist across the Morin transition in hematite.

Background

Hematite undergoes the Morin transition near 260 K, which changes the Néel-vector orientation and magnetic anisotropy. The reported measurements establish the g-wave angular dependence of the altermagnetic magnon splitting at 3.5 K, below this transition, but do not resolve whether the same splitting pattern and symmetry-protected nodes survive at technologically relevant higher temperatures and across the spin-reorientation transition. Room-temperature inelastic neutron-scattering measurements are identified as the means to test this issue.