Master of Science, Miami University, 2019, Physics

The superconducting properties of a series of Ni2ZrAl1-xGax, Ni2ZrAl1-xBx and Ni2-xCuxZrGa Heusler compounds have been explored via x-ray diffraction, scanning electron microscopy, electrical resistivity, dc magnetization, and ac susceptibility measurements. In common, all samples exhibited the cubic L21cubic structure at room temperature. For x ≥ 0.20, the Ni2ZrAl1-xBx compounds exhibited multiple phase, swerving away from the single cubic phase of the parent compound, Ni2ZrAl. All Ga doped compounds, evinced superconductivity with superconducting transition temperature, Tc, increasing with higher Ga doping while the TC of the Ni2ZrAl1-xBx compounds marginally decreased from ~ 2.2 K (x = 0) to ~ 2.0 K (x = 0.15). The Tc of 2.2 K observed for Ni2ZrAl is significantly larger than the reported value of 1.38 K. For all Cu-doped compounds, Tc decreased with increase in Cu concentration and application of magnetic field. This decrease in TC is indicative of the phase transition that occurs near zero Kelvin, quantum phase transition. The dc magnetization data suggested the type-II superconductivity for all the compounds. The experimental results with related discussion is presented in detail.

Committee: Mahmud Khan (Advisor); Herbert Jaeger (Committee Member); Samir Bali (Committee Member) Subjects: Physics