3D Magnetic Induction Maps of Nanoscale Materials Revealed by Electron Holographic Tomography

Abstract

The investigation of three-dimensional (3D) ferromagnetic nanoscale materials constitutes one of the key research areas of the current magnetism roadmap and carries great potential to impact areas such as data storage, sensing, and biomagnetism. The properties of such nanostructures are closely connected with their 3D magnetic nanostructure, making their determination highly valuable. Up to now, quantitative 3D maps providing both the internal magnetic and electric configuration of the same specimen with high spatial resolution are missing. Here, we demonstrate the quantitative 3D reconstruction of the dominant axial component of the magnetic induction and electrostatic potential within a cobalt nanowire (NW) of 100 nm in diameter with spatial resolution below 10 nm by applying electron holographic tomography. The tomogram was obtained using a dedicated TEM sample holder for acquisition, in combination with advanced alignment and tomographic reconstruction routines. The powerful approach presented here is widely applicable to a broad range of 3D magnetic nanostructures and may trigger the progress of novel spintronic nonplanar nanodevices.

Do Images of Biskyrmions Show Type‐II Bubbles?

“…This was observed in simulations of samples from 80 to 200 nm thickness (Figure S4, Supporting Information) and is a well‐known effect caused by the magnetization near the surface aligning with the stray field . It was predicted in 1973 and soon could be confirmed experimentally using the new techniques of X‐ray and electron magnetic tomography which are being developed to map magnetic structures in three dimensions …”

Review of magnetic nanostructures grown by focused electron beam induced deposition (FEBID)

“…One of the distinct features of FEBID is its capability to grow 3D structures. So far, most of the work has been focused on the growth of out-of-plane Co nanowires (30,34,36,66,68,81,88,90). The angle formed by the nanowire with the substrate can be controlled through the tilting angle of the substrate with respect to the electron beam direction (66).…”

Rytov approximation in electron scattering

“…In the particular subdiscipline of electron holographic tomography the phase grating approximation (PGA) and the Lambert-Beer law have been used to reconstruct three-dimensional distributions, of electric and magnetic potentials and the transmittance respectively, down to the scale of a few nanometers (e.g., [6], [7], [8], [9]). Both of these are linear but harsh approximations of the scattering process and they produce artifacts in certain scenarios (e.g.…”