Penetration depth of electron-doped-infinite-layer Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin films

TL;DR

This study measures the in-plane penetration depth of Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin films, revealing deviations from s-wave behavior and indicating the influence of disorder and complex gap structures in electron-doped cuprates.

Contribution

It provides new insights into the superfluid density and gap symmetry of electron-doped infinite-layer cuprates through AC susceptibility measurements.

Findings

Superfluid density deviates from s-wave behavior at higher doping.

Evidence of a nodal hole pocket or anisotropic s-wave gap.

Superconducting transition occurs in the phase-fluctuation regime.

Abstract

The in-plane penetration depth of Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin films at various doping obtained from oxygen reduction has been measured, using AC susceptibility measurements. For the higher doping samples, the superfluid density deviates strongly from the s-wave behavior, suggesting, in analogy with other electron-doped cuprates, a contribution from a nodal hole pocket, or a small gap on the Fermi surface such as an anisotropic s-wave order parameter. The low value of the superfluid densities, likely due to a strong doping-induced disorder, places the superconducting transition of our samples in the phase-fluctuation regime.