NEUTRON-SCATTERING STUDY OF SPIN-WAVES IN TBFEO3

Iron sublattice spin waves have been studied in TbFeO3 by inelastic ne utron scattering on the PRISMA spectrometer at ISIS. Magnon dispersion curves were measured along [100] and [001] directions up to energies 80 meV and the results fitted to a model taking into account near-neig bour (J(1)) and next-nearest-neigbour (J(2)) isotropic Heisenberg inte ractions. The exchange parameters J(1) = - 28.7(0.3) K and J(2) = - 1. 4(0.5) K obtained for TbFeO3 agree with those found earlier for anothe r orthoferrite TmFeO3.