Strongly correlated s-wave pairing in the n-type infinite-layer cuprate

TL;DR

This study reveals that the electron-doped infinite-layer cuprate Sr_{0.9}La_{0.1}CuO_2 exhibits strong s-wave pairing with a large, momentum-independent gap, contrasting with hole-doped cuprates and suggesting different underlying physics.

Contribution

The paper provides evidence for strongly correlated s-wave pairing in an n-type cuprate, challenging the common d-wave paradigm in cuprate superconductors.

Findings

Superconducting gap of 13.0 meV exceeds BCS value

Insignificant quasiparticle damping by spin fluctuations

Absence of pseudogap phenomena

Abstract

Quasiparticle tunneling spectra of the electron-doped (n-type) infinite-layer cuprate Sr_{0.9}La_{0.1}CuO_2 reveal characteristics that counter a number of common phenomena in the hole-doped (p-type) cuprates. The optimally doped Sr_{0.9}La_{0.1}CuO_2 with T_c = 43 K exhibits a momentum-independent superconducting gap \Delta = 13.0 +- 1.0 meV that substantially exceeds the BCS value, and the spectral characteristics indicate insignificant quasiparticle damping by spin fluctuations and the absence of pseudogap. The response to quantum impurities in the Cu-sites also differs fundamentally from that of the p-type cuprates with d_{x^2-y^2}-wave pairing symmetry.