UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Study of High Frequency Magnetisation Dynamics in Artificial Nanomagnets Using Micromagnetic Simulation and Spin Wave Spectroscopy

Dion, Troy; (2020) Study of High Frequency Magnetisation Dynamics in Artificial Nanomagnets Using Micromagnetic Simulation and Spin Wave Spectroscopy. Doctoral thesis (Ph.D), UCL (University College London). Green open access

[thumbnail of Study of High Frequency Magnetisation Dynamics in Artificial Nanomagnets Using Micromagnetic Simulation and Spin Wave Spectroscopy - Troy Dion.pdf]
Preview
Text
Study of High Frequency Magnetisation Dynamics in Artificial Nanomagnets Using Micromagnetic Simulation and Spin Wave Spectroscopy - Troy Dion.pdf - Accepted Version

Download (53MB) | Preview
[thumbnail of V1_Angle_of_Coincidence.mp4] Video
V1_Angle_of_Coincidence.mp4 - Supplemental Material

Download (121kB)
[thumbnail of V2_ASI_Resonance.mp4] Video
V2_ASI_Resonance.mp4 - Supplemental Material

Download (2MB)
[thumbnail of V3_Minor_Loops.mp4] Video
V3_Minor_Loops.mp4 - Supplemental Material

Download (3MB)
[thumbnail of V4_Kagome_Phase.mp4] Video
V4_Kagome_Phase.mp4 - Supplemental Material

Download (22MB)
[thumbnail of V5_Square_Phase.mp4] Video
V5_Square_Phase.mp4 - Supplemental Material

Download (26MB)
[thumbnail of V6_Kagome_Energy_Levels.mp4] Video
V6_Kagome_Energy_Levels.mp4 - Supplemental Material

Download (1MB)
[thumbnail of V7_Square_Energy_Levels.mp4] Video
V7_Square_Energy_Levels.mp4 - Supplemental Material

Download (1MB)
[thumbnail of V8_Square_Energy_Levels_Experimental.mp4] Video
V8_Square_Energy_Levels_Experimental.mp4 - Supplemental Material

Download (2MB)
[thumbnail of V9_Spinwave_Gate_Comparison.mp4] Video
V9_Spinwave_Gate_Comparison.mp4 - Supplemental Material

Download (16MB)
[thumbnail of V10_Spinwave_Band_Structure_for_Gates.mp4] Video
V10_Spinwave_Band_Structure_for_Gates.mp4 - Supplemental Material

Download (9MB)
[thumbnail of V11_All_Best_On_Off_Ratios.mp4] Video
V11_All_Best_On_Off_Ratios.mp4 - Supplemental Material

Download (1MB)

Abstract

Artificial spin ice (ASI) is a metamaterial comprised of magnetic nanoislands arranged in a square or hexagonal lattice. ASI has been proposed as a reconfigurable magnonic crystal to be used in spin-wave based computing technologies. It also shares the necessary properties required for hardware-based neural networks, namely, nodes connected in a non-linear network via dipole-dipole interactions and memory capacity. In order to utilise these materials for future devices the collective magnetisation dynamics need to be explored. The frequency response can be tuned via shape anisotropy modification with differential patterning, microstate control or external magnetic field magnitude and orientation. Ferromagnetic resonance (FMR), spin-wave spectroscopy and micromagnetic simulations are used to investigate these systems. Control of the shape anisotropy by modifying the length and width of the elements in each sub-lattice of ASI can alter the magnetisation dynamics, suppress or allow modes and provide routes to microstates not practically feasible in homogeneous systems. Symmetry breaking in ASI via patterning causes degeneracy lifting and allows fingerprinting of underlying microstate using FMR which is relatively easier and quicker compared to other microstate reading techniques such as scanning probe or x-ray dichromism and can be integrated into future device designs. The effect of mode shifting due to changes in local field distributions is also discussed which is a sought after property in the field of magnonics. A one-dimensional reconfigurable magnonic crystal (1D-RMC) that can be placed in any desired microstate via topological magnetic defect injection is investigated. The system is prepared in various different microstates and spin-wave propagation is characterised. The spin-wave dispersion can be controlled by changing the pitch of reversed nanoislands. We also propose a spin-wave diode design based on these findings which may be an essential component in spin-wave based computing schemes.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Study of High Frequency Magnetisation Dynamics in Artificial Nanomagnets Using Micromagnetic Simulation and Spin Wave Spectroscopy
Event: UCL
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: https://discovery.ucl.ac.uk/id/eprint/10113905
Downloads since deposit
557Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item