Correlation between superfluid density and transition temperature in infinite-layer nickelate superconductor Nd1– x Sr x NiO2

ABSTRACT The strong correlation between zero-temperature superfluid density (${{{\rho }}}_{{{\rm s}}0}$) and transition temperature (${{{T}}}_{{\rm C}}$) is considered 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 Nd0.8Sr0.2NiO2. The sample shows inhomogeneous ${{\rm{\rho }}}_{{{\rm s}}0}$ and ${{{T}}}_{{\rm C}}$ at the micron scale. The spatial statistics for different scan areas reveal a linear dependence of local ${{{T}}}_{{\rm C}}$ on ${{\rm{\rho }}}_{{{\rm s}}0}$ for ${{{T}}}_{{\rm C}} > 8\ {{\rm K}}$ and a sublinear dependence for ${{{T}}}_{{\rm C}} < 8\ {{\rm K}}$. Remarkably, the overall relationship is reminiscent of that reported in overdoped cuprate superconductors, hinting at a close connection between them.