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Characterisation and preparation of superconducting diamond films for the production of nems and squids

Werrell, Jessica 2018. Characterisation and preparation of superconducting diamond films for the production of nems and squids. PhD Thesis, Cardiff University.
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Abstract

Boron doped nanocrystalline diamond has intrinsic properties (namely a high young’s modulus to density ratio) that make it an appealing material for the construction of nano-electro-mechanical systems and superconducting quantum interference devices; which can then be used to investigate macroscopic quantum states. This thesis seeks to characterize the superconducting properties of films of this material, as measured by AC susceptibility and magnetic relaxation, in preparation for its use in the aforementioned fabrications. The properties under investigation using the AC susceptibility are the superconducting volume fraction of the sample, its critical temperature and critical current density. This thesis investigates how these properties change for diamond films grown to different thicknesses, 160 - 564 nm. It is shown that all films consist of a hundred percent superconducting material; although these typical volume fraction calculations simplify the results such that details of the transition are lost. The critical temperature is shown to be in close agreement with a critical temperature calculated considering fluctuating conduction behaviour from resistivity measurements. This thesis also gives further evidence for the recently discovered superconducting glass state within diamonds phase diagram. A pinning potential is also calculated for the thickest diamond sample in the set; which is a factor of 2 smaller than the only published value of diamond available. This difference is likely due to the growth and measurement set up variations. Finally this thesis shows how simple improvements can be made the chemical mechanical polishing of this material, which will ultimately improve device performance

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Physics and Astronomy
Subjects: Q Science > QC Physics
Uncontrolled Keywords: Superconducting, Diamond, Characterisation, Nanocrystalline, Boron, doped, NCD, BNCD, CMP, Polishing, AC susceptibility, Magnetic relaxation
Funders: Engineering and Physical Sciences Research Council, Cardiff University
Date of First Compliant Deposit: 27 March 2019
Last Modified: 28 Mar 2019 10:22
URI: http://orca-mwe.cf.ac.uk/id/eprint/121201

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