Revealing 3D magnetization of thin films with soft X-ray tomography: magnetic singularities and topological charges

A Hierro-Rodriguez,L M Alvarez-Prado,J I Martín,E Pereiro,J M Alameda,M Vélez,A Sorrentino,S Mcvitie,C Quirós,S Ferrer

doi:10.1038/s41467-020-20119-x

A Hierro-Rodriguez, L M Alvarez-Prado + Show 8 more

Open Access

https://doi.org/10.1038/s41467-020-20119-x

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Abstract

The knowledge of how magnetization looks inside a ferromagnet is often hindered by the limitations of the available experimental methods which are sensitive only to the surface regions or limited in spatial resolution. Here we report a vector tomographic reconstruction based on soft X-ray transmission microscopy and magnetic dichroism data, which has allowed visualizing the three-dimensional magnetization in a ferromagnetic thin film heterostructure. Different non-trivial topological textures have been resolved and the determination of their topological charge has allowed us to identify a Bloch point and a meron-like texture. Our method relies only on experimental data and might be of wide application and interest in 3D nanomagnetism.

Highlights

The knowledge of how magnetization looks inside a ferromagnet is often hindered by the limitations of the available experimental methods which are sensitive only to the surface regions or limited in spatial resolution
Magnetic vector tomography in extended thin films can become an essential tool for the evolution of nanomagnetism from 2D configurations to the complex 3D magnetization textures and structures explored nowadays[2] including magnetic hopfions[22] and skyrmion dots[23]
We present the first results of a 3D tomographic reconstruction of a magnetic thin film heterostructure, 240 nm thick, using transmission soft X-ray microscopy and a recently developed vector reconstruction method[21]

Summary

Introduction

The knowledge of how magnetization looks inside a ferromagnet is often hindered by the limitations of the available experimental methods which are sensitive only to the surface regions or limited in spatial resolution. We will first discuss the configuration of the domain walls by separately analyzing both tilt series, and later we will describe the magnetic singularities and determine their topological charge by analyzing both tilt series together.

Results

Conclusion