A feedback technique is presented for the reduction of the Shoenberg magnetic interaction in metals. The method allows the spin splitting parameter g[sub c] for extremal orbits on the Fermi surface to be obtained from de Haas-van Alphen measurements, now essentially free from the oft-times severe distortions resulting from magnetic interaction. The feedback technique also offers several advantageous side effects, the most important one being a simple and reliable method for determining absolute amplitudes of de Haas-van Alphen oscillations. Explicit formulae are derived showing the dependence of several key observable quantities on the amount of magnetic feedback, and these formulae are found to be in good agreement with experiment. The technique is applied to the determination of g[sub c] for the [110] γ oscillations in Pb. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

If a metal object is placed in a gravitational field, .the nuclei and electrons in the metal will sink. This will produce a new charge distribution inside the metal. A modified charge distribution implies a modified electric field in the metal interior. This thesis investigates some possible physical processes which give rise to the gravitationally induced electric field inside a metal. To this end, a simple model of a metal is constructed. Comprising the model are ions, arranged on a differentially compressed lattice, and a gas of conduction electrons. An ion is represented by a nucleus and an electron which are confined together inside a hard, massless, spherical shell. The nucleus is treated as a point particle while the electron is represented by a wave function. The conduction electron constituent is modelled as a gas of non-interacting fermions which is subject to an external linear potential, The design of the model facilitates the investigation of two possible sources of the electric field: gravitationally induced ionic dipole moments, and the charge imbalance in the metal. To first order in g, only the first source matters, contributing approximately –Mg/q[sub=e] to the electric field, where M is the ionic mass, g is the acceleration due to gravity, and q[sub=e] is the electronic charge. The net gravitationally induced electric field is also found to be approximately -Mg/q[sub=e], / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Thin films (5nm ± 2nm thick) of ZrO2, Al2O3, TiO2, Sm, Gd, Zr, Ni, and Pt were deposited onto TbFeCo films (100nm ± 20nm thick) on silicon and graphite substrates and analyzed with XPS as prospective candidates for TbFeCo diffusion barriers. Metals were chosen primarily according to electronegativity. Samples were typically heated to 272°C in UHV for 20 hours to enhance diffusion. Experiments with the metals were performed in a more consistent manner than with the oxides. The Sm, Gd, and Zr were reactively oxidized during the deposition. The Sm/Sm-oxide and Gd/Gd-oxide appeared to be favorable candidates for TbFeCo diffusion barriers. TbFeCo was not detected near the surface before or after heating the samples to 272°C for 20 hours and depth profiles indicated oxygen contamination decreased steadily as the barrier/TbFeCo interface was approached. For the other materials examined, either the oxides were reduced (at least partially) during heating to 272°C (381°C for Al₂O₃) or diffusion of TbFeCo was detected after heating, indicating that they would not be favorable candidates for TbFeCo diffusion barriers.

Several workers have previously investigated the magnetic properties of copper and aluminium, but in most cases too small regard has been paid to the changes in magnetic susceptibility brought about by mechanical and thermal treatments previous to measurements. In the present work I have attempted to correlate changes in the magnetic susceptibilities of copper and aluminium with metallurgical changes in the metal lattices. A somewhat tentative theory is outlined covering this correlation. Previous investigations by Kussmann and Seeman led to the conclusion that iron impurity in the pure copper was the sole cause of the various magnetic changes recorded. This it is hoped to disapprove. To get some insight into the changes caused by such ferromagnetic impurity a series of magnetic measurements were carried out on low iron content iron-copper alloys, very kindly supplied by Imperial Chemical Industries Ltd., “Metals Division”. The thesis falls naturally into four main parts, and appendices are added at the end to avoid interpolation of the work with definitions etc. Throughout the thesis (Parts III and IV) only a few experimental values, typical of the many results obtained, are quoted.

Ligands prepared from various combinations of aldehydes and ketones with the appropriate aminealcohol were complexed with cupric acetate monohydrate. The complexes with O,NO or N,N,O donor atoms were synthesized to study the influences of the ligand on molecular structure, spin-spin interaction, and on the value of the exchange integral. The magnetic data indicated that of the eight Cu(II) complexes discussed, two behaved differently from known analogous compounds. Cu (benzoylacetone :ethanolamine) was compared to Cu(acac:ethanolamine), and Cu(pyrr:oaminophenol) was compared to Cu(acac:o-aminophenol). Each pair of complexes was postulated to have the same molecular structure. The synthesis and characterization of Mn(pyrr:oaminophenol) 2H2 is also discussed. The following physical data were collected and discussed: elemental analysis, melting point, molecular weight, infrared spectra, electronic spectra, and magnetic susceptibility.

Call number: LD2668 .T4 1964 D44 / Master of Science

published_or_final_version / abstract / toc / Physics / Master / Master of Philosophy

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At this study three samples of hematite nanorods were deposited on the silicon substrates with different varieties of glancing angle deposition techniques. One sample (S1) was prepared by using thermal deposition with partially ionized beam (PIB) and substrate rotation. The second sample (S2) was synthesized by using thermal deposition with PIB and no substrate rotation. The third sample (S3) was obtained by using E-beam deposition, PIB and rotating substrate. In addition, one sample of magnetite nanorods (S4) has been prepared in order to compare the magnetic properties of the two different iron oxides. S4 was prepared by using thermal deposition and fixed glancing angle deposition, but no PIB was applied. The hysteresis loop has been studied for all samples and the temperature dependent magnetic properties of one of the hematite samples and the magnetite been studied, too. The studies of the magnetic hysteresis for S1, S2, S3 and S4 showed that all of the samples have hysteresis loops but with dissimilar values of the saturation magnetization Ms, remanence MR, and coercivity HC. Furthermore, the hysteresis loops of all four samples showed different behaviors as the nanorods of the samples change the orientation with respect to the magnetic field. In addition to that fact, the hysteresis loop demonstrated that samples that have similar morphology have like behavior of the hysteresis loop. Also, it has found that S2 has the largest hysteresis loop of all hematite samples and it has large hysteresis loop in the perpendicular and parallel directions with the field as well. However, the magnetite hysteresis loops are significant larger than the ones of the hematite. Likewise, the studies of the temperature dependence magnetic properties of S2 and S4 showed that the ZFC and FC M-T curves of S1and S4 behaved differently when the direction of the nanorods changed from perpendicular to parallel with the field. In addition, the ZFC and FC M-T curves of hematite were different than the ZFC and FC M-T curves of magnetite.