The pseudogap in high-temperature superconductors: an experimental survey

TL;DR

This paper provides an experimental overview of the pseudogap phenomenon in cuprate high-temperature superconductors, highlighting its characteristics, emergence, and the ongoing debate about its origin.

Contribution

It offers a comprehensive review of experimental evidence on the pseudogap, emphasizing its universal presence and relation to superconductivity, while noting the lack of consensus on its fundamental cause.

Findings

Pseudogap observed across all high-Tc cuprates

Superconducting gap emerges from the pseudogap in the normal state

Both gaps exhibit d-wave symmetry

Abstract

We present an experimental review of the nature of the pseudogap in the cuprate superconductors. Evidence from various experimental techniques points to a common phenomenology. The pseudogap is seen in all high temperature superconductors and there is general agreement on the temperature and doping range where it exists. It is also becoming clear that the superconducting gap emerges from the normal state pseudogap. The d-wave nature of the order parameter holds for both the superconducting gap and the pseudogap. Although an extensive body of evidence is reviewed, a consensus on the origin of the pseudogap is as lacking as it is for the mechanism underlying high temperature superconductivity.