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Effect of ion beam irradiation and annealing on magnetic properties of FeRh nanostructures
Zadorozhnii, Oleksii ; Turčan, Igor (oponent) ; Staňo, Michal (vedoucí práce)
The first order phase transition from antiferromagnetic to ferromagnetic state in Fe50Rh50 at 370 K make it a suitable material for next generation spin electronic devices with a low power consumption. This work deals with the ways how the phase transition temperature of iron-rhodium (FeRh) can be tuned locally in thin films, using focused ion beam (FIB) and thermal annealing. FIB irradiation approach was chosen due to the fact that FeRh displays magnetic sensitivity to the degree of its chemical ordering, which is characteristic to all alloys of ferromagnetic and non-ferromagnetic metals. Thermal annealing enables the relaxation of the structure and restoration of its crystallinity. The magnetic patterns were manufactured using gallium-based FIB and annealed under ultra high vacuum. The topography as well as magnetic behaviour of these ion irradiated patterns were investigated using atomic and magnetic force microscopies at different temperatures, showing a clear dependence between ion irradiation dose and the magnetic response in pre- and post-annealed states.
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MeV ion irradiation beamline at the Uppsala Tandem Accelerator: Improvements and applications
Sekula, Filip ; Páleníček, Michal (oponent) ; Průša, Stanislav (vedoucí práce)
The MeV ion irradiation beamline at Uppsala University's Tandem Laboratory is presented in this thesis. Theoretical basics of ion-solid collisions are discussed and material modification of solids by impinging energetic ions is described. The Tandem Accelerator setup is described starting from ion generation and ending with ions impinging on sample in irradiation beamline's main chamber. The sample transfer system is presented alongside improvements and modifications implemented to the original setup. A pilot application of improved system in material modification is presented on Ge quantum dot irradiation and ion fluence uniformity is analyzed using an electrostatic deflector simulation.
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MeV ion irradiation beamline at the Uppsala Tandem Accelerator: Improvements and applications
Sekula, Filip ; Páleníček, Michal (oponent) ; Průša, Stanislav (vedoucí práce)
The MeV ion irradiation beamline at Uppsala University's Tandem Laboratory is presented in this thesis. Theoretical basics of ion-solid collisions are discussed and material modification of solids by impinging energetic ions is described. The Tandem Accelerator setup is described starting from ion generation and ending with ions impinging on sample in irradiation beamline's main chamber. The sample transfer system is presented alongside improvements and modifications implemented to the original setup. A pilot application of improved system in material modification is presented on Ge quantum dot irradiation and ion fluence uniformity is analyzed using an electrostatic deflector simulation.
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Effect of implantation of C, Si and Cu into ZrNb nanometric multilayers
Daghbouj, N. ; Karlík, M. ; Lorinčík, J. ; Polcar, T. ; Callisti, M. ; Havránek, Vladimír
Sputter-deposited Zr/Nb nanometric multilayer films with a periodicity (L) in the range from 6 to 167 nm were subjected to carbon, silicon and copper ion irradiation with low and high fluences at room temperature. The ion profiles, mechanical proprieties, and disordering behavior have been investigated by using a variety of experimental techniques (Secondary Ion Mass Spectrometry - SIMS, nanoindentation, X-ray diffraction - XRD, and scanning transmission electron microscopy - STEM). On the STEM bright field micrographs there is damage clearly visible on the surface side of the multilayer. Deeper, the most damaged and disordered zone, located close to the maximum ion concentration, was observed. The in-depth C and Si concentration profiles obtained from SIMS were not affected by the periodicity of the nanolayers. This is in accordance with SRIM simulations. XRD and electron diffraction analyses suggest a structural evolution in relation to L. After irradiation, Zr (0002) and Nb (110) reflexions overlap for L=6 nm. For the periodicity L > 6 nm the Zr (0002) peak is shifted to higher angles and Nb (110) peak is shifted to lower angles.
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Effect of ion beam irradiation and annealing on magnetic properties of FeRh nanostructures
Zadorozhnii, Oleksii ; Turčan, Igor (oponent) ; Staňo, Michal (vedoucí práce)
The first order phase transition from antiferromagnetic to ferromagnetic state in Fe50Rh50 at 370 K make it a suitable material for next generation spin electronic devices with a low power consumption. This work deals with the ways how the phase transition temperature of iron-rhodium (FeRh) can be tuned locally in thin films, using focused ion beam (FIB) and thermal annealing. FIB irradiation approach was chosen due to the fact that FeRh displays magnetic sensitivity to the degree of its chemical ordering, which is characteristic to all alloys of ferromagnetic and non-ferromagnetic metals. Thermal annealing enables the relaxation of the structure and restoration of its crystallinity. The magnetic patterns were manufactured using gallium-based FIB and annealed under ultra high vacuum. The topography as well as magnetic behaviour of these ion irradiated patterns were investigated using atomic and magnetic force microscopies at different temperatures, showing a clear dependence between ion irradiation dose and the magnetic response in pre- and post-annealed states.
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