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

TL;DR

This study investigates how Ni substitution affects superconductivity in Fe1-xNixZr2, revealing a dome-shaped Tc dependence and potential structural transitions linked to magnetic fluctuations.

Contribution

It provides the first detailed phase diagram of Fe1-xNixZr2, showing the relationship between composition, structure, and superconductivity in CuAl2-type zirconides.

Findings

Bulk superconductivity observed for 0.4 < x < 0.8

Maximum Tc of 2.8 K at x=0.6

Dome-shaped Tc vs. x phase diagram

Abstract

CuAl2-type transition-metal (Tr) zirconides are 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. From magnetic susceptibility 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. Specific heat measurements were also performed, bulk superconductivity was observed for 0.4 < x < 0.8, and the highest Tc of 2.6 K was observed for x = 0.6. The obtained superconductivity phase diagram exhibits 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.