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Magnetic thin films for spintronic applications
Publication . Silva, Cátia Patrícia Santos da, 1987-; Cruz, Maria Margarida, 1960-
Co-N and Fe-N thin films were deposited using reactive sputtering. Different deposition conditions, varying both temperature and partial pressure (PP) of N2 in the reactive mixture, were employed in order to obtain different compositions and clarify the relation between PP(N2) and the final N content of the fillms. In order to study the relation between the the substrate choice and the obtained crystalline order of the films, different substrates were used to perform this study: glass, Al2O3, MgO and TiO2. This group of substrates was selected because of their di erent crystallographic structures, as glass is amorphous and Al2O3, MgO and TiO2 are single crystals with hexagonal, cubic and tetragonal structures, respectively. It was observed, for both Co-N and Fe-N films, that depositions performed at room temperature or on glass result in films with very poor crystalline quality. A similar trend for cobalt and iron nitrides when analyzing the prepared films as a function of PP(N2): a progression towards nitrogen richer phases as the PP(N2) during deposition was increased, associated with a decrease in the lms magnetic moment and increase in coercive field (particularly in films deposited on glass). The infl
uence of the substrate was discovered to be paramount for the films properties, inducing different orientation of growth (specially for Co-N films) and affecting the magnetic properties of the films, introducing in-plane anisotropic behavior. Single crystals of Al2O3, MgO and TiO2 were also implanted with X+N (X=Co,Fe) with energies of 110 keV and 35 keV and fl
uences of 2 1017 at/cm2 and 5 1016 at/cm2, respectively, to form nitrides embedded in the oxide matrix and study the role of the interfaces between embedded nitrides and host oxides. Lastly, samples consisting of n layers (n=2,3) of alternating Fe and Fe-N films were deposited in order to study the ifluence of the interaction and interplay between Fe and Fe-N layers on the overall magnetic properties. However, the formation of clear boundaries and consequently real multilayers was not possible, result explained by nitrogen mobility at the high temperature of deposition.
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Fundação para a Ciência e a Tecnologia
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SFRH
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SFRH/BD/70150/2010