Holographic Vector Field Electron Tomography of Three-Dimensional Nanomagnets

TL;DR

This paper demonstrates a holographic vector field electron tomography technique capable of reconstructing all three components of magnetic induction and electrostatic potential in 3D nanomagnets with nanometer resolution, enabling detailed magnetic characterization.

Contribution

The authors introduce a workflow for 3D magnetic field reconstruction in nanostructures using holographic electron tomography, providing new insights into magnetic textures and their dependence on nanostructure variations.

Findings

Reconstructed magnetic induction and electrostatic potential with sub 10 nm resolution.

Identified how small structural variations affect magnetization configurations.

Derived local magnetic properties such as magnetization current and exchange stiffness.

Abstract

Complex 3D magnetic textures in nanomagnets exhibit rich physical properties, for example in their dynamic interaction with external fields and currents, and play an increasing role for current technological challenges such as energy-efficient memory devices. To study these magnetic nanostructures including their dependency on geometry, composition and crystallinity, a 3D characterization of the magnetic field with nanometer spatial resolution is indispensable. Here we show how holographic vector field electron tomography can reconstruct all three components of magnetic induction as well as the electrostatic potential of a Co/Cu nanowire with sub 10\,nm spatial resolution. We address the workflow from acquisition, via image alignment to holographic and tomographic reconstruction. Combining the obtained tomographic data with micromagnetic considerations we derive local key magnetic characteristics, such as magnetization current or exchange stiffness, and demonstrate how magnetization configurations, such as vortex states in the Co-disks, depend on small structural variations of the as-grown nanowire.