Oblique magnetic anisotropy and domain texture in Bi3 Fe5 O12 films

Abstract

Magnetic iron garnet films with perpendicular magnetic anisotropy (PMA) are highly desirable for spintronics and magnonics applications. In this study, we have grown single-phase epitaxial Bi3Fe5O12 films on a Gd3Ga5O12 substrate with (111) orientation. The nondestructive sin2ψ technique of the x-ray diffraction measurement demonstrates the negative value of residual stress, suggesting the compressive nature of stress in the system. Ferromagnetic resonance and magnetic force microscopy (MFM) have been used to probe the magnetic anisotropies and magnetic domain texture, respectively. In-plane (IP) angular variation of the resonance field Hr reveals a weak IP magnetic anisotropy with pronounced sixfold and fourfold symmetries in 15 and 10 nm thick films, respectively. For the 15 nm thick film, the out-of-plane angular variation of Hr shows oblique magnetic anisotropy with the magnetic easy axis making an angle of 25∘ with respect to the film plane. The oblique magnetic easy axis is further confirmed with θ mapping of the MFM image. However, for the 10 nm thick film there is complete reorientation of the magnetic easy axis perpendicular to the film plane. The cubic magnetocrystalline anisotropy along with the magnetoelastic anisotropy overcomes the shape anisotropy and leads to negative effective magnetic anisotropy Keff and PMA. MFM images show a labyrinthine mazelike domain texture, typical of iron garnet films with PMA. © 2023 American Physical Society.