Spectroscopic evidence for preformed Cooper pairs in the pseudogap phase of cuprates

TL;DR

This study provides spectroscopic evidence that preformed Cooper pairs exist in the pseudogap phase of cuprates, suggesting it is a precursor to superconductivity, with implications for understanding high-temperature superconductivity.

Contribution

It offers direct spectroscopic evidence of preformed Cooper pairs in the pseudogap phase, linking it to superconductivity in cuprates.

Findings

Dispersion shows two branches characteristic of Bogoliubov quasiparticles.

Superconducting and pseudogaps share the same d-wave form and amplitude.

Evidence supports the pseudogap phase as a precursor to superconductivity.

Abstract

Angle-resolved photoemission on underdoped La$_{1.895}$Sr$_{0.105}$CuO$_4$ reveals that in the pseudogap phase, the dispersion has two branches located above and below the Fermi level with a minimum at the Fermi momentum. This is characteristic of the Bogoliubov dispersion in the superconducting state. We also observe that the superconducting and pseudogaps have the same d-wave form with the same amplitude. Our observations provide direct evidence for preformed Cooper pairs, implying that the pseudogap phase is a precursor to superconductivity.