Evidence for pairing above Tc from the dispersion in the pseudogap phase of cuprates

TL;DR

This paper provides evidence that above the critical temperature in cuprates, electronic excitations exhibit pairing characteristics without global superconducting coherence, suggesting preformed pairs in the pseudogap phase.

Contribution

It demonstrates that the dispersion in the pseudogap phase indicates pairing without condensation, challenging competing order explanations.

Findings

Dispersion behaves like a normal metal on Fermi arcs.

Gapped regions show superconductor-like dispersion.

Supports the existence of preformed pairs above Tc.

Abstract

In the underdoped high temperature superconductors, instead of a complete Fermi surface above Tc, only disconnected Fermi arcs appear, separated by regions that still exhibit an energy gap. We show that in this pseudogap phase, the energy-momentum relation of electronic excitations near E_F behaves like the dispersion of a normal metal on the Fermi arcs, but like that of a superconductor in the gapped regions. We argue that this dichotomy in the dispersion is hard to reconcile with a competing order parameter, but is consistent with pairing without condensation.