Impact of further-range exchange and cubic anisotropy on magnetic excitations in the fcc kagome antiferromagnet Ir Mn3

This work investigates the effects of further neighbor exchange and cubic anisotropy on the magnetic excitations of the fcc kagome antiferromagnet Ir Mn 3 . Spin wave frequencies are calculated using the torque equation and the dynamical structure factor S ( Q , ω ) is determined by a Green's function method as an extension of our previous work [LeBlanc et al. Phys. Rev. B 90, 144403 (2014)]. These spin wave calculations are compared with inelastic neutron scattering data of polycrystalline Ir Mn3, where magnetic Mn ions occupy lattice sites of ABC-stacked kagome planes. The data are best explained by a spin wave model including exchange interactions up to fourth nearest neighbor and strong cubic anisotropy, as previously predicted by density functional theory calculations.