Effect of cation site occupancy on the structure and magnetic properties of SrCoxTixFe12–2xO19 thin films.

Multiferroic materials have potential applications in multifunctional electronic devices, and M-type hexaferrite with conical spin order is a promising candidate. In this paper, a series of SrCo x Ti x Fe 12–2x O 19 thin films were prepared by a sol-gel method, and x-dependent structure, cation site occupancy and magnetic properties were investigated to explore the origin of conical spin order in M-type hexaferrite. It was found that the introduction of Co2+ and Ti4+ ions decreases the uniaxial magnetocrystalline anisotropy and breaks the threefold symmetry of the lattice, inducing a conical magnetic structure. Moreover, the appearance temperature of the conical spin order (T cone) increases first and then decreases with the increase of x, and the largest T cone of about 324 K is obtained in SrCo 1.8 Ti 1.8 Fe 8.4 O 19 thin film. The evolution of magnetization is closely related to the site occupancy of Co2+ and Ti4+ ions, and the net effective substitution ratio of spin-down Fe3+ is positive correlation to the T cone of SrCo x Ti x Fe 12–2x O 19 and thus considered to be responsible for the introduction of conical spin order. The results reveal the correlation between the structure, magnetic properties and cation site occupancy, pointing out an effective method to induce conical spin order in M-type hexaferrites. • The net effective substitution of Co2+-Ti4+ to spin-down Fe3+ correlates with T cone. • The selective substitution to spin-down Fe3+ induces conical spin order. • The introduction of Co2+ and Ti4+ ions can induce local non-zero DM interaction. [ABSTRACT FROM AUTHOR]