Equivalence of pseudogap and pairing energy in a cuprate high-temperature superconductor

TL;DR

This study provides clear evidence that the pseudogap in cuprate high-temperature superconductors is directly related to electron pairing, with the pseudogap energy matching the pairing energy and indicating that phase coherence limits the critical temperature.

Contribution

The paper offers unambiguous experimental evidence linking the pseudogap to pairing energy, supporting the pairing scenario over local order hypotheses in cuprates.

Findings

Pseudogap energy coincides with the onset of electron pairing.

Pseudogap exhibits spatial heterogeneity up to 70 meV.

Results exclude a pure local order origin of the pseudogap.

Abstract

The pseudogap stands out in the phase diagram of the cuprate high-temperature superconductors because its origin and relationship to superconductivity remain elusive. The origin of the pseudogap has been debated, with competing hypotheses attributing it to preformed electron pairs or local order, such as charge density waves. Here, we present unambiguous evidence supporting the pairing scenario, using local shot-noise spectroscopy measurements in Bi2Sr2CaCu2O8+{\delta}. Our data demonstrates that the pseudogap energy coincides with the onset of electron pairing, and is spatially heterogeneous with values reaching up to 70 meV. Our results exclude a pure local order origin of the pseudogap, link the pseudogap to Cooper pair formation, and show that the limiting factor for higher Tc in cuprates is phase coherence.