Magnetoelectric Coupling Triggered by Noncollinear Magnetic Structure in M‐Type Hexaferrite.

Direct magnetoelectric (ME) coupling between magnetic and ferroelectric orders, which can be realized in spiral magnets, is vital in technological applications of multifunctional materials. Multisusceptible BaFe12O19 is noteworthy for its excellent magnetic, dielectric properties and thus the application in high‐density information storage, while its collinear spin structure limits the emergence of ferroelectrics and ME coupling. In this work, nonzero Dzyaloshinskii–Moriya (DM) interaction is created by partial substitution of the spin‐down Fe3+ sites to induce conical spin structure in BaFe12O19. Larger In3+ ions are introduced and prefer to occupy the spin‐down 4f1 and 4f2 lattice sites. The evolution of magnetization versus temperature adduces evidence of conical magnetic structure. As a result, direct ME and magnetodielectric coupling are obtained in In‐doped BaFe12O19 ceramics. An interlayer DM interaction model is built to discuss the intrinsic relationship among crystal structure, noncollinear magnetic structure, and ionic substitution. Moreover, BaZn0.9Zr0.9Fe10.2O19 ceramics are also prepared, and exhibit noncollinear magnetic structure and direct ME coupling since Zn2+ and Zr4+ also possess larger radii than Fe3+ and prefer to enter the spin‐down sites. The present result provides a feasible avenue to develop multiferroic and magnetoelectric coupling in ubiquitous M‐type hexaferrite. [ABSTRACT FROM AUTHOR]