Theses and Dissertations at Montana State University (MSU)

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    A neutron diffraction and NMR study of ferroelectric and antiferroelectric ordering in CsH2PO4 at high pressure
    (Montana State University - Bozeman, College of Letters & Science, 1988) Schuele, Paul John
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    Comparison of the Kirchhoff and Rayleigh-Rice diffractions for sinusoidal surfaces
    (Montana State University - Bozeman, College of Engineering, 1990) Schiff, Tod Forrest; Chairperson, Graduate Committee: Frederick M. Cady; John C. Stover (co-chair)
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    Fresnel diffraction with small apertures
    (Montana State University - Bozeman, College of Letters & Science, 1991) Struckhoff, Andrew David
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    A semi-quantitative x-ray diffraction technique for estimation of smectite, illite, and kaolinite
    (Montana State University - Bozeman, College of Agriculture, 1981) Hopper, Roger W. E.
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    Objective lens for a miniature endoscopic confocal microscope
    (Montana State University - Bozeman, College of Engineering, 2005) El Ferradi, Nabil; Chairperson, Graduate Committee: David Dickensheets
    This thesis presents the design and testing of a micro-objective lens for a miniature endoscopic confocal microscope. The advance of confocal endo-microscopy for in-situ imaging can lead to considerable improvements in inspection, analysis, and diagnosis, especially in the biomedical field. The dimensions of the objective lens developed are 4.0 mm long and 2.0 mm in diameter incorporated into a probe that is 2.0 mm in diameter and 10.0 mm long. The size of the probe will allow it to be inserted in some of the smallest channels in an endoscope. The objective lens features a 0.33 numerical aperture, a 4x magnification, and 200 æm field of view and a sub-micron spot size. The optical system is compensated at two wavelengths, 488 nm and 515 nm. Chromatic and spherical aberrations are minimized through the use of 3 refractive planoconvex elements and an 8-level fused silica diffractive optical element. Details of the lens design, its simulation using computer ray tracing software, fabrication of the diffractive optical element and experimental characterization of the assembly are presented.
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    Epitaxial thin film deposition of magnetostrictive materials and its effect on magnetic anisotropy
    (Montana State University - Bozeman, College of Letters & Science, 2012) McClure, Adam Marc; Chairperson, Graduate Committee: Yves U. Idzerda; Steven Albert, Tino Jaeger, Hongyan Li, Paul Rugheimer, Juergen A. Schaefer and Yves U. Idzerda were co-authors of the article, 'Properties of single crystal Fe 1-xGa x thin films' in the journal 'Journal of applied physics' which is contained within this thesis.; Elke Arenholz and Yves U. Idzerda were co-authors of the article, 'Ferrimagnetic ordering of single crystal Fe 1-xGa x thin films' in the journal 'Journal of vacuum science and technology A' which is contained within this thesis.; Hongyan Li and Yves U. Idzerda were co-authors of the article, 'Magnetostrictive effect in single crystal Fe 1-xGa x thin films' in the journal 'Journal of applied physics' which is contained within this thesis.; Paul Rugheimer and Yves U. Idzerda were co-authors of the article, 'Magnetic and structural properties of single crystal Fe 1-xZn x thin films' in the journal 'Journal of applied physics' which is contained within this thesis.
    Magnetostriction means that the dimensions of a material depend on its magnetization. The primary goal of this dissertation was to understand the effect of magnetostriction on the magnetic anisotropy of single crystal magnetostrictive thin films, where the epitaxial pinning of the material to a substrate could inhibit its conversion to new dimensions. In order to address this goal, several Fe-based binary alloys were deposited onto various substrates by molecular beam epitaxy. The samples were characterized by an array of techniques including electron diffraction, Rutherford backscattering, vibrating sample magnetometry, ferromagnetic resonance, and x-ray absorption spectroscopies. The attempted growths of crystalline magnetostrictive thin films resulted in successful depositions of Fe 1-xGa x and Fe 1-xZn x. Depositions onto MgO(001) substrates result in an in-plane cubic magnetic anisotropy, as expected from the cubic symmetry of the Fe-based thin films, and a strong out-of-plane uniaxial anisotropy that forces the magnetization to lie in the plane of the films. Depositions onto ZnSe/GaAs(001) substrates feature an additional in-plane uniaxial anisotropy. The magnitudes and signs of the in-plane anisotropies depend on the Ga content. Furthermore, the cubic anisotropy constant of Fe 1-xGa x samples deposited onto MgO substrates switches sign at a lower Ga concentration than is seen in bulk Fe 1-xGa x. The effect on the magnetic anisotropy of depositing a magnetostrictive material as an epitaxial thin film is influenced by the material's magnetostrictive properties and the substrate upon which it is deposited. In particular, pinning a magnetoelastic material to a substrate will modify its cubic anisotropy, and depositions on substrates compliant to an anisotropic strain relaxation may result in a strong in-plane uniaxial anisotropy.
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