A study of the 6Ssub(5/2)-term splitting of an Fe3+ ion in zinc ferrite by neutron spectroscopy

Inelastic neutron scattering studies are carried out on a zinc ferrite at temperatures between 5 and 293 K. It is found that the 6Ssub(5/2)-term of Fe3+ ion at the B-sites is split into six levels. Transitions between these levels are observed both in energy gain and energy loss configurations. The 6Ssub(5/2)-term splitting and observed neutron spectra are discussed on the basis of a phenomenological spin-Hamiltonian assuming combined interaction of a static magnetic field and a static electric field gradient with magnetoelectric moments of 3d5 electron shell, respectively. The quadrupole moment due to deformation process of 3d5 shell is assumed as being caused by trigonal deformation of octahedral B sites and by exchange interaction. It is found that the internal magnetic field acting on Fe3+(B) ions is about 320 kOe and is directed along one of the equivalent directions [100], [010], or [001]. The parameter of quadrupole interaction is D=-0.667 meV. The shape of 3d5 shell deformation is established as spindle-like. As a result of mixed magnetoelectric interaction of Fe3+(B) ions, the magnetic moment is lowered to 4.0 BM at 5 K. The obtained data are compared with magnetization against temperature. A test of the proposed magnetization process is carried out by Moessbauer effect measurements in external magnetic fields. (author)