Unambiguous evidence for extended s-wave pairing symmetry in hole-doped high-temperature superconductors

TL;DR

This study provides clear experimental evidence supporting extended s-wave pairing symmetry with eight line nodes in optimally doped Bi_2Sr_2CaCu_2O_8+y high-temperature superconductors, challenging the d-wave model.

Contribution

The paper presents a comprehensive analysis combining multiple experimental techniques to definitively identify extended s-wave symmetry in high-Tc superconductors.

Findings

Data inconsistent with d-wave symmetry

Results align with extended s-wave symmetry with eight line nodes

All phase-sensitive experiments are coherently explained

Abstract

We have analyzed data from angle resolved photoemission spectroscopy, Fourier transform scanning tunnelling spectroscopy, and low-temperature thermal conductivity for optimally doped Bi_2Sr_2CaCu_2O_8+y in order to discriminate between d-wave and extended s-wave pairing symmetry. The combined data are inconsistent with d-wave symmetry, but quantitatively consistent with extended s-wave symmetry with eight line nodes. We also consistently explain all the phase-sensitive experiments.