Magnetic textures in a hexaferrite thin film and their response to magnetic fields revealed by phase microscopy

We investigated magnetic textures in a Sc-doped hexaferrite film by means of phase microscopy with a hole-free phase plate in a transmission electron microscope. In a zero magnetic field, the stripe-shaped magnetic domains coexist with magnetic bubbles. The magnetization in both magnetic domains was oriented perpendicular to the film and the domain walls have an in-plane magnetization. In the remnant state at 9.2 mT, a number of magnetic bubbles were formed with the formation of stripe-shaped magnetic domains, and the out-of-plane component in the stripe-shaped domains gradually appeared as the film thickness increased. As the film thickness increased further, the magnetic bubbles with clockwise or counterclockwise spin helicities formed a triangular lattice. These results in the remnant state suggest that the domain-wall energy in the magnetic bubble domains is lower in the thicker region. (C) 2019 The Japan Society of Applied Physics