The Micromagnetism of Video Recording Tracks Written on CoNi Metal Evaporated Tape (MET)

Sinclair, George John (1990) The Micromagnetism of Video Recording Tracks Written on CoNi Metal Evaporated Tape (MET). PhD thesis, University of Glasgow.

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Abstract

The main objective of the work described in this thesis was to study the micromagnetic structure of 8mm video recording tracks. We attempted to quantify the written magnetisation patterns and correlate the results with the bulk magnetic characteristics of each of the different samples analysed. We studied the micromagnetics as a function of the physical and magnetic characteristics of the films and also the wavelength of the recorded signal. The basic principles of ferromagnetism are outlined in chapter 1, and then in chapter 2 we describe the way in which the technology of magnetic recording harnesses these properties. Chapter 2 also provides details of the recording format used in video 8. This section concludes with the demands now placed on the physical and magnetic characteristics of the materials which these high storage density applications require. The high resolution required to examine the written tracks necessitates the use of electron microscopy and chapter 3 describes the basic beam specimen interactions and illustrates the ways in which contrast can be produced which relates to the magnetisation within the sample. Chapter 4 details the specific requirements of the Differential Phase Contrast (DPC) mode of Lorentz Electron Microscopy which have to be met if quantitative interpretation of the information is to be possible. This section also indicates the operational limits of this technique and the relevance of these on the results. The next 3 chapters (5-7) contain the results which form the main body of this thesis. The fabrication procedure of the films and the physical and compositional characterisation of the samples is detailed in chapter 5. Chapter 6 contains the results of the bulk magnetic characterisation of these MET films The quantitative micromagnetic results obtained from each film, at two recording densities, form the basis of chapter 7. We also detail small angle scattering experiments which were necessary to establish the validity of the quantitative results. The final chapter, chapter 8, suggests ways in which we feel that much of the information which we obtained, about the micromagnetic structure of the recorded samples, could be improved now that the DPC system has recently been modified. We also comment on the relevance of new techniques now available and how these might add to our existing knowledge of the micromagnetic structure produced within ferromagnetic materials when subjected to localised magnetic fields.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Electromagnetics
Date of Award: 1990
Depositing User: Enlighten Team
Unique ID: glathesis:1990-78195
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:37
Last Modified: 30 Jan 2020 15:37
URI: http://theses.gla.ac.uk/id/eprint/78195

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