BaM hexaferrite (BaFe$_{12}$O$_{19}$) thin films on Al$_2$O$_3$ (01–12) substrates: crystal structure and magnetic properties

Epitaxial films of BaM hexaferrite (BaFe$_{12}$O$_{19}$) with a thickness of 50 nm were grown on R-cut sapphire $\alpha$-Al$_{2}$O$_{3}$ (01–12) substrates by laser molecular beam epitaxy (LMBE). Their crystal structure and magnetic properties were studied before and after post-growth annealing. It was found that in the annealed films obtained by the LMBE method, the easy axis of magnetic anisotropy is deviated from the normal to the surface, which makes it possible to switch the magnetization with both normal and tangential magnetic fields, and leads to the dependence of the hysteresis loop shape on the field orientation in the film plane.