Superconductivity in La$_2$Ni$_2$In

TL;DR

This study investigates La$_2$Ni$_2$In single crystals, revealing it as a weakly correlated metal that becomes a dirty type-II superconductor below 0.9 K, with s-wave symmetry and effects from ferromagnetic nanoclusters.

Contribution

It provides the first detailed characterization of superconductivity and magnetic properties in La$_2$Ni$_2$In, combining experimental measurements with DFT calculations.

Findings

Superconductivity observed below 0.9 K.

La$_2$Ni$_2$In is a weakly correlated metal.

Identified as a dirty type-II superconductor with s-wave gap symmetry.

Abstract

We report here the properties of single crystals of La$_2$Ni$_2$In. Electrical resistivity and specific heat measurements concur with the results of Density Functional Theory (DFT) calculations, finding that La$_{2}$Ni$_{2}$In is a weakly correlated metal, where the Ni magnetism is almost completely quenched, leaving only a weak Stoner enhancement of the density of states. Superconductivity is observed at temperatures below 0.9$\,$K. A detailed analysis of the field and temperature dependencies of the resistivity, magnetic susceptibility, and specific heat at the lowest temperatures reveals that La$_2$Ni$_2$In is a dirty type-II superconductor with likely s-wave gap symmetry. Nanoclusters of ferromagnetic inclusions significantly affect the subgap states resulting in a non-exponential temperature dependence of the specific heat $C(T)$ at $T\ll T_\text{c}$.