Correlation between superfluid density and transition temperature in infinite-layer nickelate superconductor $N{d}_{1-x}S{r}_{x}Ni{O}_2$

Abstract

A strong correlation between zero-temperature superfluid density ($\ddot{I}{}_{s0}$) and transition temperature ($T_c$) is considered as a hallmark of unconventional superconductivity. However, their relationship has yet to be unveiled in nickelates due to sample inhomogeneity. Here we perform local susceptometry on an infinite-layer nickelate superconductor $N{d}_{0.8}S{r}_{0.2}Ni{O}_2$. The sample shows inhomogeneous superfluid density and $T_c$ on micron-scale. The spatial statistics for different scan areas reveal a linear dependence of local $T_c$ on $\ddot{I}{}_{s0}$ for $T_c$>8 K and a sub-linear one for $T_c$<8 K. Remarkably, the overall relationship is reminiscent of that reported in overdoped cuprate superconductors, hinting at a close connection between them.