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 groundJ= 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 atT_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.