Hyperfine fields in iron-rich ferromagnetic alloys
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The initial aim of the research was to study hyperfine fields in iron-rich FeCo and FeNi alloys by means of nuclear magnetic resonance (NMR), In addition projects fundamental to NMR were carried out. Modulation broadening was studied by calculating the line shapes of Lorentz and Gaussian resonances detected at the first three harmonics of the modulation frequency for a number of modulation amplitudes. Methods of correcting observed line shapes for modulation broadening were developed and evaluated by applying them to the calculated broadened line shapes. This work is described in Chapter 2.
The application of the Kronig-Kramers relationships to the analysis of dispersion mode records is discussed in Chapter 3, This project was carried out in collaboration with Professor H.C. Bolton and Mr. G.J. Troup. The author was responsible for the computational techniques and the application to modulation broadened line shapes.
In Chapter 1 fundamentals of NMR are described. In Chapter 4 the present state of experimental methods and theory relevant to hyperfine fields in ferromagnets is briefly described. Apart from these two review chapters and portions of Chapter 3 results quoted without a reference refer to the original work of the author.
The apparatus employed in an experimental study of hyperfine fields in iron-rich alloys is described in Chapter 5. In Chapter 6 NMR line shapes of iron and iron-rich FeCo and FeNi alloys are described. These results are then compared with recently reported Mossbauer and neutron diffraction measurements. Implications of these with regard to angular and radial dependences of the interaction between an impurity and host atom are discussed.
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