# $d$-wave superconducting gap observed in protect-annealed electron-doped cuprate superconductors Pr$_{1.3-x}$La$_{0.7}$Ce$_{x}$CuO$_{4}$

## TL;DR

This study uses angle-resolved photoemission spectroscopy to reveal a $d$-wave superconducting gap in protect-annealed electron-doped cuprates, indicating persistent strong electron correlations and potential antiferromagnetic spin fluctuation mediation.

## Contribution

First direct observation of a $d$-wave superconducting gap in protect-annealed electron-doped cuprates using ARPES, highlighting the role of strong correlations.

## Key findings

- Superconducting gap consistent with $d$-wave symmetry.
- Strong electron correlations persist after protect-annealing.
- Antiferromagnetic spin fluctuations remain a candidate for pairing mechanism.

## Abstract

For electron-doped cuprates, the strong suppression of antiferromagnetic spin correlation by efficient reduction annealing by the "protect-annealing" method leads to superconductivity not only with lower Ce concentrations but also with higher transition temperatures. To reveal the nature of this superconducting state, we have performed angle-resolved photoemission spectroscopy measurements of protect-annealed electron-doped superconductors Pr$_{1.3-x}$La$_{0.7}$Ce$_{x}$CuO$_{4}$ and directly investigated the superconducting gap. The gap was found to be consistent with $d$-wave symmetry, suggesting that strong electron correlation persists and hence antiferromagnetic spin fluctuations remain a candidate that mediates Copper pairing in the protect-annealed electron-doped cuprates.