Using electrons to fabricate and characterise three-dimensional ferromagnetic nanostructures

Šilinga, Aurys (2026) Using electrons to fabricate and characterise three-dimensional ferromagnetic nanostructures. PhD thesis, University of Glasgow.

Abstract

The study of electronics that utilise the spin of electrons has led to significant technological developments for data storage applications. The manufacturing of electronics on flat substrates is well established, and hence electron spin tends to be integrated into two-dimensional (2D) computer chips and data storage devices by design. This work investigates how spintronics may be extended to three-dimensional (3D) nanoscale structures. The additive manufacturing method of focused electron beam induced deposition (FEBID) is optimised for the fabrication of free-standing ferromagnetic nanowires (NWs). Vertical and angled NWs are tailored to exhibit consistent compositional and magnetic properties, which enhances the fabrication of free-standing spintronic circuits. The advanced transmission electron microscopy (TEM) method of off-axis electron holography is used to characterise the magnetic configurations in a 3D ∧-shaped NW structure, and a method is developed for tomographic reconstruction of magnetisation in 3D. The tomographic method, based on model-based iterative reconstruction (MBIR), incorporates tomographic alignment and image-distortion correction algorithms, enabling experimental reconstruction of a 3D magnetisation vector field with a spatial resolution of 50 nm. To assess the applicability of the reconstruction method to other datasets, simulations are performed that test known limitations of TEM methods. The effects of a limited range of sample rotations are evaluated in simulations of NWs. It is found that spatial averaging between the vacuum and the sample surface can occur when tomographic datasets contain too few projections. In addition, Néel domain walls (DWs) and Bloch points are simulated to test how the MBIR algorithm treats magnetic configurations that are conventionally invisible to TEM. The reconstruction is limited to revealing only magnetic moments that create detectable signals. Overall, methods were developed for the fabrication of consistently ferromagnetic 3D NW structures and for the characterisation of 3D magnetic configurations within them.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Almeida, Dr. Trevor and Fallon, Dr. Kayla
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-85961
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 22 May 2026 13:36
• Last Modified: 22 May 2026 13:37
• Thesis DOI: 10.5525/gla.thesis.85961
• URI: https://theses.gla.ac.uk/id/eprint/85961

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