Tuning the Magnetic Order in Sc-Substituted Barium Hexaferrites

Abstract

Polycrystalline BaFe _12-x Sc _x O ₁₉ hexaferrites (x = 0.1, 0.6, and 1.2), produced using ceramic technology, have hexagonal structure with space group (P63/mmc) as determined by neutron powder diffraction. Magnetic properties were analyzed by vibrating sample magnetometry and Mössbauer spectroscopy. Tuning the magnetic parameters by Sc substitution is associated with several factors: first, ordering the Sc ³⁺ ions in positions 2b and 4f ₂ and the cation vacancies at the boundary of the spinel and hexagonal blocks; second, transfer of spin density from Fe ions localized at position 12k to 3d orbitals of Sc ³⁺ ions; third, weakening the indirect exchange interactions between 2b, 4f ₂ , and 12k sublattices; and finally, presence of a noncollinear magnetic order for Sc concentration x above 0.6.