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A platform for research: civil engineering, architecture and urbanism
Towards the miniaturization of core-shell cylindrical structures: fabrication and characterization of ferromagnetic core-shell micro- and nanowires
The aim of the work reported in this thesis has been the development of a nanoparticle, which, due to its unique, optimized morphology, displays no magnetic stray fields. Since a similar configuration has been fabricated within the frames of this work on the microscale using core-shell microwires, the thesis focuses towards the miniaturization of ferromagnetic cylindrical core-shell nanostructures. Here the design, fabrication, and investigation of ferromagnetic core-shell cylindrical structures at the micro- and nanoscale, consisting of two ferromagnetic phases separated by a non-ferromagnetic intermediate layer and predefined magnetic properties, is elucidated. The thesis consists of three parts: (i) the fabrication and investigation of core-shell structures, followed by (ii) the micromagnetic simulations of the magnetization reversal of core-shell nanowires, which suggest the optimal particle materials and dimensions to move towards their miniaturization, and, finally, (iii) the development and implementation of a novel fabrication method for short core-shell nanowires fabrication, with optimized control over the material selection and geometrical parameters of the constituents. (i) Core-shell microwires with amorphous FeSiB and crystalline CoSiB cores and Co, CoNi, and FeNi external shells separated by a Pyrex layer, have been fabricated by the combined Ulitowski-Taylor, sputtering and electrodeposition technique. Moreover, a partially covered core-shell microwire has been fabricated and investigated for the first time. The effect of the external shell geometry (partial or full shell), thickness, and composition on the overall magnetic response of the system has been investigated at room temperature, as well as in the temperature range T=295-1200K. It has been shown that the external shell drastically modifies the magnetic behavior of the microwire, making it possible to tune the overall magnetic properties as desired via the magnetostatic and magnetoelastic coupling between the ferromagnetic core and shell. ...
Towards the miniaturization of core-shell cylindrical structures: fabrication and characterization of ferromagnetic core-shell micro- and nanowires
The aim of the work reported in this thesis has been the development of a nanoparticle, which, due to its unique, optimized morphology, displays no magnetic stray fields. Since a similar configuration has been fabricated within the frames of this work on the microscale using core-shell microwires, the thesis focuses towards the miniaturization of ferromagnetic cylindrical core-shell nanostructures. Here the design, fabrication, and investigation of ferromagnetic core-shell cylindrical structures at the micro- and nanoscale, consisting of two ferromagnetic phases separated by a non-ferromagnetic intermediate layer and predefined magnetic properties, is elucidated. The thesis consists of three parts: (i) the fabrication and investigation of core-shell structures, followed by (ii) the micromagnetic simulations of the magnetization reversal of core-shell nanowires, which suggest the optimal particle materials and dimensions to move towards their miniaturization, and, finally, (iii) the development and implementation of a novel fabrication method for short core-shell nanowires fabrication, with optimized control over the material selection and geometrical parameters of the constituents. (i) Core-shell microwires with amorphous FeSiB and crystalline CoSiB cores and Co, CoNi, and FeNi external shells separated by a Pyrex layer, have been fabricated by the combined Ulitowski-Taylor, sputtering and electrodeposition technique. Moreover, a partially covered core-shell microwire has been fabricated and investigated for the first time. The effect of the external shell geometry (partial or full shell), thickness, and composition on the overall magnetic response of the system has been investigated at room temperature, as well as in the temperature range T=295-1200K. It has been shown that the external shell drastically modifies the magnetic behavior of the microwire, making it possible to tune the overall magnetic properties as desired via the magnetostatic and magnetoelastic coupling between the ferromagnetic core and shell. ...
Towards the miniaturization of core-shell cylindrical structures: fabrication and characterization of ferromagnetic core-shell micro- and nanowires
Iglesias, Irene (author) / Farle, Michael
2020-11-16
Theses
Electronic Resource
English
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