Determination of the exchange anisotropy in perovskite antiferromagnets using powder inelastic neutron scattering

A procedure is outlined for the determination of magnetic exchange constants in anisotropic perovskite anitferromagnets using powder inelastic neutron scattering. Spin wave densities-of-states are measured using time-of-flight inelastic neutron scattering for LaMnO$_{3}$ ($A$-type antiferromagnet), LaVO$_{3}$ ($C$-type), and LaFeO$_{3}$ ($G$-type) and compared to Heisenberg model calculations. The anisotropy of in-plane ($J_{ab}$) and out-of-plane ($J_{c}$) exchange constants can be obtained from the data. The procedure quickly determines the magnetic exchange interactions without the need for single-crystal dispersion measurements and allows for rapid systematic studies of the evolution of magnetism in perovskite systems.