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

TL;DR

This study uses phase microscopy to reveal complex magnetic textures in a Sc-doped hexaferrite thin film, showing how magnetic domains and bubbles evolve with magnetic field and film thickness.

Contribution

It provides detailed visualization of magnetic domain structures and their response to magnetic fields in a hexaferrite thin film, a novel application of phase microscopy.

Findings

Magnetic domains coexist as stripes and bubbles in zero field.

Magnetic bubbles form a triangular lattice at higher film thickness.

Out-of-plane magnetization increases with film thickness.

Abstract

We investigated magnetic textures in a Sc-doped hexaferrite film by means of phase microscopy (PM) 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, several 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 increases further, the magnetic bubbles with clockwise or counter-clockwise 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.