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Title: Adsorbate influences on ferromagnetic surfaces
Author: Gunn, D. S. D.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2010
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In this thesis, we highlight the importance of thin-film magnetism and use density functional theory (DFT) calculations to investigate how the surface magnetic properties of several ferromagnetic (FM) systems can be altered through gas-phase adsorption. We begin by looking at the ferromagnetic fcc Co{110} surface, taking note of the structural, electronic and magnetic properties it possesses with a view to its potential use in novel magnetoelectronic devices. We identify crucial modifications that occur to the surface properties upon adsorption of varying quantities of hydrogen, boron, carbon, nitrogen, oxygen and fluorine. With a wide range of adsorbates, we investigate the similarities and differences between adsorption of a much smaller range of species on several different FM surfaces. Here we are comparing adsorption of carbon, nitrogen and oxygen on fcc iron, cobalt and nickel surfaces, and looking in particular at their influence on the surface layer spin magnetic moment. Following this, we study the influence of oxygen and nitrogen on a specific magnetic property that can be measured experimentally – the second electron spin polarisation (SESP). We introduce a novel theoretical method for calculating the SESP from our ab initio simulations which shows excellent agreement with the experimental measurements. Here, adsorption is modelled on fcc Co{100} surfaces. Continuing to investigate large-scale magnetic properties of thin-film systems, we initially compare and contrast three different facets of bi-layered Co/Co surfaces and then investigate several multilayered arrangements where two FM layers are separated by a non-magnetic ‘spacer’ layer. These systems can have layers that are aligned ferromagnetically or anti-ferromagnetically, and preference for either alignment is controlled via the interlayer exchange coupling. We investigate this effect in the ultrathin regime, and with fcc Co/Cu/Co and Fe/Cu/Co systems.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available