Sign change in c-axis thermal expansion constant and lattice collapse by Ni substitution in transition-metal zirconide superconductor Co_1-xNi_xZr₂.

ABSTRACT: Recently, c-axis negative thermal expansion (NTE) was observed in a CoZr₂ superconductor and related transition-metal zirconides. Here, we investigated the structural, electronic, and superconducting properties of Co_1-xNi_xZr₂ to achieve systematic control of c-axis NTE and switching from NTE to positive thermal expansion (PTE) by Ni substitution. At x ≤ 0.3, c-axis NTE was observed, and the thermal expansion constant α_c approached zero with increasing x. At x = 0.4-0.6, c-axis thermal expansion close to zero thermal expansion (ZTE) was observed, and PTE appeared for x ≥ 0.7. On the superconducting properties, we observed bulk superconductivity for x ≤ 0.6, and bulk nature of superconductivity is suppressed by Ni heavy doping (x ≥ 0.7).

SUBMITTER: Watanabe Y 

PROVIDER: S-EPMC9849259 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature