An inelastic neutron scattering investigation of holmium orthoferrite

The inelastic neutron scattering spectra recorded in this study and elsewhere provide a useful set of crystal-field (CF) energy levels for the ground J = 6 term of Ho3+ in HoFeO3. The resolution of the low-energy, temperature-dependent pseudo-quadrupole ground state splitting and magnon peaks is consistent with the self-ordering of the Ho3+ sublattice at T Ho ∼ 8-10 K and supports earlier electron spin resonance investigations of the Ho3+ magnon behaviour. Systematic analysis of the grouped singlet CF levels of Ho3: HoFeO3, in conjunction with the CF Kramers doublet levels of the neighbouring Er3+: ErFeO3, has yielded possible sets of CF parameters for the two systems.