Magnetic Origin of Giant Magnetoelectricity in Doped Y-type Hexaferrite Ba 0.5 Sr 1.5 Zn 2 ( Fe 1 − x Al x ) 12 O 22

摘要: We investigated site-specific magnetic behaviors of multiferroic ${\mathrm{Ba}}_{0.5}{\mathrm{Sr}}_{1.5}{\mathrm{Zn}}_{2}({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{)}_{12}{\mathrm{O}}_{22}$ using Fe ${L}_{2,3}$-edge x-ray circular dichroism. The Al dopants mostly replace the ${\mathrm{Fe}}^{3+}$ ions at octahedral (${O}_{h}$) sites, which contribute unquenched angular momenta through off-centering displacements. This replacement greatly reduces anisotropy energy to change order from a helical heliconical type with enhanced magnetoelectric susceptibility (${\ensuremath{\alpha}}_{\mathrm{ME}}$). tetrahedral (${T}_{d}$) sites exhibit hysteresis distinguishable that ${O}_{h}$ especially low fields. These results provide essential clues for giant ${\ensuremath{\alpha}}_{\mathrm{ME}}$ and multibit memory effects in Al-doped Y-type hexaferrite.