Novel antimony-based Heuslers with potential spintronic applications

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University of Alabama Libraries

The Heusler alloys, or compounds to be precise, have become a well-known name among materials scientists, solid-state physicists and other researchers of the field. In this set of studies, we examined a ternary system, i.e. Fe-Ti-Sb using experimental methodology comprised of different microstructural and structural tests alongside theoretical evaluations. The results showed that there was a compound present in the system, Fe1.5TiSb, which had the structural hall marks of a Heusler, albeit with vacancies in the tetragonal positions. This meant that the compound not only was most probably ‘layered’ between half a full Heusler, but also it was paramagnetic, the compound exhibited a novel Slater-Pauling behavior. The next system studied was FexCo1-xTiSb, eventually leading to observation of a novel half Heusler compound, Fe0.5Co0.5TiSb. The compound showed a C1b signature and no sign of any other phase were witnessed microstructurally. Magnetometry and transport measurements revealed the nature of the material to be an antiferromagnetic material with possible semiconductivity. Theoretical evaluations further validated the possibility of an antiferromagnetic coupling between iron and cobalt in this compound. Following the discovery of the Fe1.5TiSb, colleagues in our theory group encouraged us to look into another possible ‘layered’ Heusler, Co1.5TiSn, based on the former compound’s prototype. The experiments not only found that the Co1.5TiSn has all the hallmarks of a Heusler, but also magnetometry tests, especially the interesting evaluation of a Rhodes-Wohlfarth model, led to conclusion that the compound has half-metallic characteristics. The bandstructure calculated through first-principles methods also initially predicated this half metallic nature.

Electronic Thesis or Dissertation
Materials science, Condensed matter physics