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Magnetic shape memory alloys: Effects of doping with Cu and Fe
Kancko, Andrej ; Colman, Ross Harvey (advisor) ; Uhlířová, Klára (referee)
In this thesis, the focus is set on studying the properties of Ni-Mn-Ga magnetic shape memory (MSM) alloys, ferromagnetic Heusler compounds, codoped with Fe and Cu. Codoping Ni-Mn-Ga MSM alloys with Fe and Cu had previously been studied due to a synergy in increasing the martensitic transformation temperature - a key parameter for practical applications of the magnetic shape memory effect. We present the preparation process of five Ni-Mn-Ga-Fe-Cu single crystals using the optical floating zone method, as well as the analysis of their composition, crystal structure and magnetic properties, performed following the growth. The results obtained from our single crystals were finally compared with the data from the previously studied polycrystalline Ni-Mn-Ga-Fe-Cu alloys, showing similar trends in increasing the martensitic transformation temperature, the Curie temperature and the saturation magnetisation.
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Synthesis and Characterization of Topological crystalline insulators in the SnTe material class
Chovanec, Jakub ; Uhlířová, Klára (advisor) ; Prokleška, Jan (referee)
k bakalářské práci - Anglický jazyk Synthesis and Characterization of Topological crystalline insulators in the SnTe material class Jakub Chovanec July 21, 2017 In this work we prepared series of single crystal samples PbxSn1−xTe and PbxSn1−xSe. These materials are quite popular last few years, after they were predicted and then char- acterized by [4] as topological crystaline insulators (TCI). TCI is a quantum state of crys- tals, in which symetry causes existance of the metal states on the surface. Samples had been prepared from molten flux and by using Bridgman method. Homogenity and pu- rity of single crystals had been determined. Compounds PbxSn1−xTe and PbxSn1−xSe crystalized in cubical structure and were defined as Fm-3m space group, existance of PbxSn1−xSe in Pnma space group were confirmed. 1
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