a Study of the Electron-Phonon Interaction in the Dhva Effect

Available from UMI in association with The British Library. This thesis is concerned with an experimental investigation of the influence of the electron-phonon interaction on the de Haas-van Alphen (dHvA) effect. Mercury was selected as the most favourable metal for this study, attention being focused on the beta-orbit, because of its relatively low frequency and effective mass. A major part of the investigation has been concerned with the accurate measurements of the amplitude of the dHvA effect and its field dependence for comparison with the theories of Lifshitz and Kosevich (LK) (1956) and Engelsberg and Simpson (ES) (1970). Experiments have been made for the first time at fields in the range 1-8 T and at temperatures between 1.3-4.2 K. The results show striking deviations from the semiclassical theory of Lifshitz and Kosevich which are in reasonable quantitative agreement with the theory of Engelsberg and Simpson. Contrary to a claim by Elliott et al (1980) we find the Dingle temperatures are the same for the different dHvA harmonics. Our experiments also reveal that the apparent effective mass, deduced from the temperature dependence of the dHvA amplitude, is strongly field dependent. We show this to be consistent with the ES theory and to be a further indication of the breakdown of quasiparticle behaviour in the dHvA effect. Some preliminary studies have been made on the beta -orbit in indium using a top-loading dilution refrigerator to perform dHvA experiments at 20mK in fields extending to 13T. We conclude that the many-body theoretical approach of ES provides a good description of the influence of the electron-phonon interaction on the dHvA amplitudes.