Revealing 3D Magnetization of Thin Films with Soft X-ray Tomography: Closure Domains and Magnetic Singularities

TL;DR

This paper demonstrates 3D imaging of internal magnetization structures in ferromagnetic thin films using soft X-ray tomography, revealing complex domain configurations and magnetic singularities previously inaccessible.

Contribution

It introduces a novel 3D tomographic method for visualizing internal magnetization in thin films, capturing features like closure domains and singularities.

Findings

Revealed 3D magnetic domain structures and closure domains.

Identified meron singularities and Bloch points inside the film.

Demonstrated extension potential to spintronics applications.

Abstract

The knowledge of how the magnetization looks inside a ferromagnet is often hindered by the limitations of the available experimental methods that are sensitive only to the surface regions or limited in spatial resolution. We report the 3D tomographic reconstruction of the magnetization within a ferromagnetic film of 240 nm in thickness using soft X ray microscopy and magnetic dichroism. The film has periodic magnetic domains forming stripes and closure domains found to be shifted from the stripe array by 1/4 of the period. In addition, the bifurcations of the stripes, which act as inversion nuclei of the magnetization, evidence in 3D meron singularities and Bloch points at the interior of the film. This novel method can be easily extended to magnetic stacks in spintronics applications and other singularities in films.