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The quantum mechanical origin of the Einstein-De Haas effect

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Title: The quantum mechanical origin of the Einstein-De Haas effect
Authors: Wells, Tomos J.
Item Type: Thesis or dissertation
Abstract: Understanding properties such as heat transfer coefficients in steels and how magnetic fields affect the microstructure and plasticity of reactor components is critical to both the materials selection process and the structural design of nuclear fusion tokamaks. Calculating these properties in ferromagnetic materials presents a challenge for modern computational materials science, since modelling the thermal effects in magnetic materials requires a description of spin-lattice coupling for systems involving large numbers of atoms. In this thesis, a noncollinear tight binding model capable of describing the coupling between spins and forces experienced by the lattice due the electrons is developed, which includes the effects of spin-orbit coupling, coupling to an external magnetic field, and vector Stoner exchange. This model is used to investigate the Einstein-de Haas effect in the context of an O2 dimer and an Fe15 cluster. In both cases, an external time-varying magnetic field is found to produce a mechanical torque on the lattice nuclei, validating that the tight binding model is able to simulate the Einstein-de Haas effect.
Content Version: Open Access
Issue Date: Dec-2021
Date Awarded: Jun-2022
URI: http://hdl.handle.net/10044/1/98124
DOI: https://doi.org/10.25560/98124
Copyright Statement: Creative Commons Attribution NonCommercial Licence
Supervisor: Horsfield, Andrew
Foulkes, William
Sponsor/Funder: CCFE
Department: Materials
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Materials PhD theses

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