The dispersion relation E ( q ) for spin waves in Cr 2 O 3 has been measured at 78 K by means of inelastic neutron scattering using a triple-axis spectrometer. Thespin-wave energy is found to vary between 7.9 K (0.68 meV) at the Brillouin zone centre to 635 K (54.7 meV) at the zone boundary near (111). The data were fitted to a theoretical E ( q ) derived from a Heisenberg Hamiltonian involving neighbours out to about 6.1 Å distance. It is found that the interactions to the first and second neighbours are strong, but weak interactions exist out to at least the fifth neighbours (4.1 Å). The sublattice magnetization, the Néel point, the Curie-Weiss temperature and the perpendicular susceptibility are calculated using the spin-wave data and are found to agree well with observations. The density of spin-wave states is also calculated.
Inelastic neutron scattering investigation of spin waves and magnetic interactions in Cr2O3 
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