Two-dimensional characterization of three-dimensional magnetic bubbles in Fe$_3$Sn$_2$ nanostructures

TL;DR

This study uses advanced TEM techniques to directly visualize complex 3D magnetic skyrmion bubbles in Fe$_3$Sn$_2$ nanostructures, revealing the significance of 3D magnetization in magnetic characterization.

Contribution

It introduces a method to identify and analyze 3D magnetic skyrmion bubbles in nanostructures using TEM, highlighting the importance of 3D effects in magnetic imaging.

Findings

Direct visualization of 3D magnetic skyrmion bubbles

Numerical models reproduce experimental magnetic structures

3D magnetization significantly impacts magnetic characterization

Abstract

We report differential phase contrast scanning transmission electron microscopy (TEM) of nanoscale magnetic objects in Kagome ferromagnet Fe$_3$Sn$_2$ nanostructures. This technique can directly detect the deflection angle of a focused electron beam, thus allowing clear identification of the real magnetic structures of two magnetic objects including three-ring and complex arch-shaped vortices in Fe$_3$Sn$_2$ by Lorentz transmission electron microscopy imaging. Numerical calculations based on real material-specific parameters well reproduced the experimental results, showing that the magnetic objects can be attributed to integral magnetizations of two types of complex three-dimensional (3D) magnetic skyrmion bubbles with depth-modulated spin twisting. Magnetic configurations obtained using the high-resolution TEM are generally considered as two-dimensional (2D) magnetic objects previously. Our results imply the importance of the integral magnetizations of underestimated 3D magnetic structures in 2D TEM magnetic characterizations.