Electrical & Computer Engineering
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Item Dependence of the perpendicular anisotropy in Co/Au multilayers on the number of repetitions(American Institute of Physics, 2003-05-15) Gubbiotti, G.; Carlotti, G.; Albertini, F.; Casoli, F.; Bontempi, E.; Depero, L. E.; Mengucci, P.; Di Cristoforo, A.; Koo, H.; Gomez, R. D.The correlations between structure and magnetism in [Co(0.9 nm)/Au(5 nm)]XN multilayer films with different number of repetitions N510, 30, and 50, have been studied by the combined use of complementary structural and magnetic techniques, such as x-ray reflectivity, x-ray diffraction, and transmission electron microscopy, alternating gradient force magnetometry, magnetic force microscopy and Brillouin light scattering. On increasing the value of N, an overall improvement of the multilayer quality is observed which corresponds to a change in the micromagnetic structure and to an enhancement of the perpendicular anisotropy. These effects have been attributed to a reduction of the magnetostatic energy associated with the formation of perpendicular magnetic domains in multilayers with increasing number of layers repetitions.Item Development of Magnetic Field Sensors Using Bismuth - Substituted Garnets Thin Films with In-Plane Magnetization(2006-04-24) NISTOR, IULIAN; Mayergoyz, Isaak D.; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In this thesis, the use of magnetic single crystal Bismuth-substituted Iron Garnet thin-films with giant magneto-optical effect as optical sensors for measuring low intensity magnetic fields over a high frequency range (up to 1GHz) is discussed. The advantages of these optical sensors are high intrinsic sensitivity and the possibility of tailoring the field range of the sensor. Such sensors could find applications in various industry and research fields where high sensitivity and electric isolation are required, such as power industry, vehicle detection, and read heads for recording magnetic media with high-density and high transfer rates. The thesis has three major components that correspond, in order, to the following topics: garnet growth, characterization and actual device design. First, the liquid phase epitaxy method is discussed for the growth of single crystal epitaxial garnet thin films of high optical quality. Second, the garnet thin films are fully characterized using various magnetic and optical techniques. Novel optical techniques are suggested, that allow the local measurement of properties such as magnetostriction constants and magnetic anisotropy of garnets. The results of these extensive measurements allow for the identification of melt compositions and growth conditions that yield thin garnet films with in-plane magnetization, giant Faraday rotation per unit length, large negative uniaxial anisotropies and small cubic anisotropy, as required for the sensing applications. In the end, the design of magnetic field sensors based on single and multi-layer garnet thin films is demonstrated, and devices are built for measurements of response and noise equivalent fields. Under the category of sensors, another sensing application is included, that utilizes garnet thin films for direct imaging of two-dimensional fringing magnetic fields with sub-micron resolution.