We use high rate magnetically-confined-plasma-triode sputtering guns in a diffusion pumped vacuum chamber to fabricate metal-metal superlattices. By feedback control of the sputtering rates and microprocessor control of the substrate rotation the individual layer thicknesses were kept constant to within ±0.3% over the entire sample thickness ∼0.5 μm. We describe in detail the results of a number of structural characterization techniques applied to these materials, including Bragg Θ-2Θ x-ray diffraction, transmission and reflection Laue diffraction, wide film Debye-Scherrer diffraction, and Rutherford Backscattering Spectrometry (RBS). By depositing Ta onto freshly deposited Mo surfaces and using RBS to measure the resultant Ta coverage we determined the dependence of the Ta sticking coefficient on coverage. The same was done for Mo deposited on Ta surfaces. We grew a series of Mo/Ta superlattices with superlattice wavelengths covering the range from 10 to 120 Å. A number of four-wire resistance measuring patterns were etched in each superlattice using standard photolithographic techniques. Resistivities of the superlattice films of various layer thicknesses were then measured to a relative precision of 0.01% and an absolute accuracy of 1%. The layer thickness dependence and temperature coefficient of the resistivity of these superlattices was analyzed using grain and size effect theories.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

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Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for: School of Engineering. Bibliography: leaves 170-185. Also available online via the Internet.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 155-176). Also available in electronic version.

Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: J. M. Xu. Includes bibliographical references (leaves 112-121). Also available online.

Acoustic modes guided by thin-film metal superlattices have been investigated using Brillouin spectroscopy. Samples were grown on both single-crystal sapphire and fused silica substrates by alternately sputtering two different metals to yield a total thickness in the range 0.3 - 0.5 μm. Structural and chemical characterization of the polycrystalline films was performed using x-ray diffraction. Rutherford backscattering and optical interferometry. Thermally excited acoustic waves in the metal film create a surface ripple which weakly interacts with light incident from a single mode argon laser. A tandem Fabry-Perot consisting of two synchronized 3-pass cavities is used to measure the frequency shift of light which is inelastically scattered from acoustic waves. The contrast ratio of this interferometer exceeds 10¹⁰ and provides sufficient stray light rejection to detect the surface Rayleigh wave and as many as 13 higher order acoustic modes. The elastic stiffness constants of the anisotropic superlattices were estimated by fitting the measured acoustic mode velocities to a parameterized acoustic model. A comparison is made between these elastic constants and those predicted from the properties of the separate bulk constituents. The dependence of bilayer wavelength on the elastic properties of both Cu/Nb and Mo/Ta superlattices over the range of roughly 10 to 200 Å was determined. The unexpected softening of Cu/Nb superlattices within a range of bilayer wavelengths near 20 Å which was reported previously is qualitatively similar to the measurements reported here. It is shown that the elastic stiffness coefficient with the largest variation is c₄₄. The stiffness variations determined for the Mo/Ta samples are much smaller than for Cu/Nb. It is suggested that this is due to either structural differences (Cu/Nb is fcc-bcc and Mo/Ta is bcc-bcc) or the smaller interfacial lattice mismatch for Mo/Ta. Interfacial strain is found to be strongly correlated with the stiffness variations of the Mo/Ta samples. However, the underlying cause of these variations in stiffness remains anomalous. This dissertation also reports the first observations of Love waves and Stoneley waves by Brillouin scattering. The purely transverse Love waves guided by Cu/Nb films were detected by elasto-optic scattering from the evanescent acoustic strain in the sapphire substrate. The stiffness coefficient c₁₂ of the hexagonally symmetric metal film cannot be determined by the other guided acoustic waves which ripple the surface. Molybdenum in contact with fused silica is predicted to support a Stoneley wave which is guided by the interface. The lowest order Sezawa made guided by a molybdenum film was found to evolve to the Stoneley wave as the film becomes thicker. These measurements together with measurements of the surface Rayleigh wave show that the stiffness of the sputtered metal films is quite homogeneous and independent of film thickness.

Computer simulations invoking the Metropolis Algorithm and Monte Carlo techniques were constructed to model the behavior ofvarious systems of magnetic semiconductors. Among the systems modeled were bulk type II FCC antiferromagnets and simple cubic thin films and superlattices. Studies of bulk antiferromagnets revealed dependence of Neel Temperature on nearest neighbor interactions as well as next nearest neighbor contributions in contradiction to mean field theory. Thin film studies revealed the effects of film thickness on critical temperature as well as differing magnetization curves for different portions of the fIlm. Superlattice simulations showed agreement with experimental data regarding anisotropy studies and also investigated the correlation beween interlayer and intralayer ordering in a superlattice. These simulations predict that interlayer coupling begins either at a temperature equal to that of the onset of intralayer ordering or at some higher temperature. / Graduation date: 2004

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaf 137). Also available on the Internet.