The vortex-Nernst effect in a superconducting infinite-layer nickelate

TL;DR

This study measures the Nernst and Seebeck effects in Nd$_{1-x}$Sr$_x$NiO$_2$ thin films, revealing a vortex-liquid state over a broad temperature range near the superconducting transition.

Contribution

It provides the first detailed observation of vortex-Nernst signals and upper-critical fields in nickelate superconductors, highlighting similarities to cuprate high-$T_c$ materials.

Findings

Vortex-Nernst signal observed with a maximum at 5 T

Upper-critical field $H_{c2}$ remains large up to 15 T at 11 K

Evidence of a vortex-liquid state over a wide temperature range

Abstract

We report measurements of the Nernst and Seebeck effects in Nd$_{1-x}$Sr$_x$NiO$_2$ thin films near the superconducting transition temperature, $T$ = 6.5 - 15 K. Our main result is the observation of a vortex-Nernst signal $S_{yx}(T,H)$ with a maximum at $\mu_0H$ = 5 T and a tail that extends to $\mu_0H$ $\approx$ 15 T, which we identify as the upper-critical field $H_{c2}$. At $T > T_{\rm c} =$ 6.1 K, $H_{c2}$ remains large (15 T), up to the highest temperature we can resolve from $S_{yx}$ (11 K). These results indicate the existence of a vortex-liquid state over a wide range of finite-resistance temperatures, as in the high-$T_{\rm c}$ cuprates.