Superconducting properties and electronic structure of CuAl2-type transition-metal zirconide Fe1-xNixZr2

Abstract

CuAl2-type transition-metal (Tr) zirconides are a superconductor family, and the Tr-site element substitution largely modifies its transition temperature (Tc). Here, we synthesized polycrystalline samples of Fe1-xNixZr2 by arc melting. The crystal structure and the superconducting properties were studied through synchrotron X-ray diffraction, magnetic susceptibility, electrical resistivity, and specific heat measurements. Bulk superconductivity was observed for 0.4 ≤ x ≤ 0.8, and the highest Tc of 2.8 K was observed for x = 0.6. The obtained superconductivity phase diagram exhibits a dome-shaped trend, which is similar to unconventional superconductors, where magnetic fluctuations are essential for superconductivity. In addition, from the c/a lattice constant ratio analysis, we show the possible relationship between the suppression of bulk superconductivity in the Ni-rich compositions and a collapsed tetragonal transition.