Spin-wave spectrum for barium ferrite

Abstract
We describe the calculation of the spin‐wave spectrum for barium ferrite, a complex exchange‐coupled hexagonal ferrimagnetic compound, using a method first used in a similar calculation for yttrium iron garnet (YIG). The exchange integrals are calculated by fitting the Weiss molecular field approximation to the sublattice magnetizations while including single‐ion anisotropy. The value for the space‐averaged stiffness constant as calculated from the acoustic mode of the spin‐wave spectrum is 2.5×109 Oe cm2, which compares favorably with values obtained by domain wall resonance, considering the accuracy of such measurements.