Spin waves in the rare-earth orthorferrite YFeO${}_3$ have been studied by inelastic neutron scattering and analyzed with a full four-sublattice model including contributions from both the weak ferromagnetic and antiferromagnetic orders. Antiferromagnetic exchange interactions of $J_1=-4.23\pm 0.08$ (nearest neighbors only) or $J_1=-4.77\pm 0.08$ meV and $J_2=-0.21\pm 0.04$ meV lead to excellent fits for most branches at both low and high energies. An additional branch associated with the weak antiferromagnetic order was observed. This work paves the way for studies of other materials in this class containing spin reorientation transitions and magnetic rare-earth ions.

• Received 11 September 2013
• Revised 20 December 2013

DOI:https://doi.org/10.1103/PhysRevB.89.014420