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Non-resonant microwave absorption studies in SmFeAs(O,F) iron pnictide superconductor

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dc.contributor.advisor Vallabhapurapu, Vijaya Srinivasu Onyancha, Robert Birundu 2016-03-10T09:30:47Z 2016-03-10T09:30:47Z 2015-03
dc.identifier.citation Onyancha, Robert Birundu (2015) Non-resonant microwave absorption studies in SmFeAs(O,F) iron pnictide superconductor, University of South Africa, Pretoria, <> en
dc.description.abstract As an electromagnetic response detection technique, non-resonant microwave absorption (NRMA) has been without doubt, one of the fundamental tools in characterizing high temperature superconductors (HTSC). The technique can explicitly give factual information on flux pinning, granularity, magnetization, and detection of iota superconducting phases among many more. The emergence of iron pnictides superconductors has brought an enormous impact on HTSC field due to their relatively high 𝑇c, high critical fields 𝐵c2, huge critical current density and low anisotropy. Accordingly, they look appealing candidates in industrial applications more especially in high magnetic field applications. As of yet, its electromagnetic response particularly the low field microwave absorption (LFMA) or the non-resonant microwave absorption (NRMA) is relatively unknown. Consequently, in this work, systematic studies have been done on SmFeAs(O,F), superconductors to determine the low field sweep microwave absorption. Furthermore, effect of varying temperature, microwave power and field modulation amplitude on NRMA line shape have been addressed and the results obtained are compared with NRMA results of cuprates superconductors. Interestingly, the NRMA line shape has been found to evolve as a function of temperature, microwave power and field modulation amplitude. A structure i.e a broad peak 1 and a narrow peak 2 have been identified. Furthermore, the line shape shows a phase reversal at moderately high microwave power. This dissertation presents the theoretical background of superconductors, experimental techniques, working principles of the equipments, results, discussions and conclusions. As pertains to the future work, recommendations have been suggested in trying other forms of sample and also different sample materials of iron based superconductors to fully understand the NRMA and ensure a progressive and continuous work in this field. Also, we will carry out extensive studies on critical current density, fluxon dynamics and irreversibility fields on iron-based superconductors by means of NRMA technique. en
dc.format.extent 1 online resource (x, 95 leaves) : illustrations
dc.language.iso en en
dc.subject.ddc 537.623
dc.subject.lcsh High temperature superconductors
dc.subject.lcsh Superconductors
dc.title Non-resonant microwave absorption studies in SmFeAs(O,F) iron pnictide superconductor en
dc.type Dissertation en
dc.description.department Physics M. Sc. (Physics)

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