Magnetic Anisotropy of Magnetoplumbite BaFe₁₂O₁₉

Abstract

The ground state splitting of Fe³⁺ in a strong trigonal field is studied theoretically in order to account for the uniaxial anisotropy of hexagonal crystal BaFe₁₂O₁₉. The spin Hamiltonian DS_z² is derived as the second-order contribution of the spin-orbit interaction, the crystal field being treated as a part of the unperturbed Hamiltonian. It is shown that reasonable values of crystal field parameters lead to the observed value of D∼−2.0 cm⁻¹.