科研之友
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摘要
The magnetic anisotropy change of Co-Ti substituted Sr-M hexaferrite has been investigated by using general gradient approximation (GGA) with on-site coulomb repulsion added (GGA + U) and force theorem method. The calculated dependence of magnetic anisotropy energy on angles of SrFe12O19 fits very well with theoretical description, and anisotropy constant K-1 agrees well with experimental value. The impact of occupancy of Co2+ and Ti4+ on magnetic anisotropy in SrCo2Ti2Fe8O19 has been studied. The results show that Co2+ in 4f2 site and Ti4+ in 12 k site both contribute to the reduction of uniaxial magnetic anisotropy, and as Co2+ and Ti4+ in their first preference of substitution site, magnetic anisotropy of SrCo2Ti2Fe8O19 is weak, which would facilitate the formation of conical magnetic structure to induce electric polarization. As substitution rate x increases from 0 to 3, the magnetic anisotropy of SrCoxTixFe12-2xO19 is found to change from uniaxial to planar.
