Studies in magnetoelasticity
Abstract:
This thesis is divided into two halves: the first reports on the study of surface acoustic waves (SAWs) in thin magnetic films and their magnetoelastic coupling with spin waves; the second describes a study of magnetoelastic torque sensors used in electric bicycles.
Chapter 1 motivates the need for alternative computing architectures to improve performance and reduce energy consumption. One such alternative, spin-wave computing, is introduced, alongside a possible energy-efficient mechanism for spin-wave excitation using SAWs.
Chapter 2 describes the experimental process used to fabricate yttrium iron garnet zinc oxide heterostructures, in which the coupling between SAWs and spin waves can be studied.
Chapter 3 sets out a theoretical model to determine the properties of SAWs in thin film multilayers. Chapter 4 outlines a theoretical model to describe the coupling of SAWs with spin waves.
Chapter 5 presents the micro-focused Brillouin light scattering data used to analyse the samples. Firstly, the SAW transducer frequency response and SAW group velocities are measured; following this, data showing the coupling of SAWs with spin waves is presented. The coupling is highly non-reciprocal, which agrees with the predictions from the theoretical model. Finally, in Chapter 6, concluding remarks on this first part of the thesis are given.