Amorphous metals have been studied extensively recently and possess many interesting electronic properties. This thesis aims to examine some of these, with particular reference to the conductivity and Hall effect in such alloys. In an extensive review of recent theoretical and experimental work, the author attempts to examine (i) whether the data can be explained using the 'semi-classical' theory of transport, with the inbuilt assumption that the electron loses memory of all collisions before that immediately preceding the time of observation, or whether 'quantum interference' and 'electron correlation phenomena must be considered, and (ii) whether it is possible to provide a simple physical picture of such quantum interference phenomena which leads to results commensurate with those of formal theories and with experimental results. A good probe of electron correlation effects is the temperature dependence of the Hall coefficient. In conjunction with the conductivity a good idea of the importance of such phenomena can be obtained. The succeeding chapters discuss the rebuilding of a radio frequency sputtering system suitable for production of thin amorphous metal films, and the methods used in making high precision measurements of the properties mentioned, between 1.25 and 300K. A results chapter reports data taken on the Cu-Ti and Ni-Zr systems, which were chosen as representative transition metal - transition metal alloy systems showing a wide range of behaviour. Extensive analysis of these data is undertaken, in terms of quantum interference and other theories. The effects of clustering of magnetic centres, and of superconductivity, in Ni-Zr films, is discussed. It is shown that the results are in broad agreement with these theories and first evidence is presented that electron correlation phenomena may be affected by inelastic electron scattering at intermediate temperatures. Confirmation of a simple relationship between the change in Hall coefficient and of conductivity due to electron correlation, predicted by theory, is provided. A short conclusion makes suggestions for future experimental work.

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by So Koon Chong. / Bibliography: leaves 86-88 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

The purpose of this investigation was to study some of the transport effects in a single crystal of arsenic at liquid helium temperatures in a magnetic field up to twenty-four kilogauss. The experimental coefficients determined were the isothermal magnetoresistivity and the isothermal Hall resistivity.

Bilayer magnetic nanostructures are currently of interest in a variety of applications due to the ability to combine complementary properties of each layer. One key area is data storage where extending hard disk drive (HDD) storage density may be achieved by storing each bit of data in an individual magnetic nanostructure. Whilst several magnetometry techniques are capable of measuring the properties of arrays of magnetic nanostructures, very few are sensitive enough to measure an individual magnetic nanostructure. An electrical technique termed anomalous Hall effect (AHE) magnetometry is used in this work due to its high sensitivity. In this technique the structure is fabricated on a Hall cross, and a current is applied and the transverse voltage measured whilst sweeping an external magnetic field. Bilayer magnetic nanostructures formed from separated Co/Pd and Co/Ni multilayers were measured for the first time with this technique, which showed that an asymmetry is seen in their hysteresis loops when the two layers are magnetically decoupled. It is demonstrated that this is due to a combination of a very small giant magnetoresistance (GMR) effect present in the magnetic nanostructure, and the Hall cross offset voltage which results from small imperfections in the shape of the cross. A finite element simulation is used to provide quantitative evidence for this model. These results indicate that asymmetry will be seen in Hall measurements of other materials which exhibit magnetoresistance. Bilayers of FePt and FeRh were also investigated as these materials are of interest for a future HDD system where the structure is heated, and the FeRh undergoes a ferromagnetic transition causing it to assist the switching of the FePt. These thin films are difficult to deposit whilst achieving chemical ordering in both layers. FeRh/FePt films are deposited, before greater ordering is demonstrated with an FePt/FeRh film. It is demonstrated that AHE magnetometry can provide a similar level of measurement information of bilayer nanostructures of these materials as bulk magnetometry techniques can provide of the thin film.

The development of the conductivity coefficients is reviewed for both highly degenerate metals, having an energy dependent relaxation time, and semiconductors, obeying Boltzmann statistics and having a relaxation time varying as the energy to the λ power.

La diffusion (e,e'p) est un outil privilégié pour l'étude de la structure nucléaire, en particulier dans le cas des noyaux légers où des calculs exacts sont possibles. L'avènement d'accélérateurs d'électrons de grande énergie et de grand cycle utile a ouvert l'accès au domaine des grandes impulsions, permettant de sonder la structure nucléaire à des distances inférieures à la taille du nucléon et de mesurer d'éventuels effets liés à leur structure interne. Ce mémoire présente une sélection du programme expérimental récemment effectué dans le Hall A du Jefferson Laboratory dans le cadre de cette problématique. Une attention particulière est portée sur la mise en évidence et la compréhension de la dynamique des mécanismes de rediffusion. L'étude de la structure interne du nucléon est également abordée à travers le phénomène de Transparence de Couleur - mettant à profit la dominance des effets de ré-interaction en diffusion quasi-élastique sur les noyaux légers - et les distributions généralisées de partons mesurables en diffusion Compton profondément inélastique.

Thesis (M.A.)--University of Wisconsin--Madison, 1968. / Title from title screen (viewed Mar. 30, 2007). Includes bibliographical references. Online version of the print original.