The nodal gap component as a good candidate for the superconducting order parameter in cuprates

TL;DR

This paper argues that the nodal gap component in cuprates is the most likely candidate for the superconducting order parameter, based on its scaling with critical temperature and temperature dependence across doping levels.

Contribution

It provides experimental evidence that the nodal gap component is the true superconducting order parameter in cuprates, distinguishing it from the antinodal gap linked to the pseudogap.

Findings

Nodal gap scales with $T_c$ across doping levels.

Nodal gap shows significant temperature dependence below $T_c$.

Two distinct gaps exist in underdoped cuprates.

Abstract

Although more than twenty years have passed since the discovery of high temperature cuprate superconductivity, the identification of the superconducting order parameter is still under debate. Here, we show that the nodal gap component is the best candidate for the superconducting order parameter. It scales with the critical temperature $T_c$ over a wide doping range and displays a significant temperature dependence below $T_c$ in both the underdoped and the overdoped regimes of the phase diagram. In contrast, the antinodal gap component does not scale with $T_c$ in the underdoped side and appears to be controlled by the pseudogap amplitude. Our experiments establish the existence of two distinct gaps in the underdoped cuprates.