Evidence for pairing above the transition temperature of cuprate superconductors from the electronic dispersion in the pseudogap phase

Phys Rev Lett. 2008 Sep 26;101(13):137002. doi: 10.1103/PhysRevLett.101.137002. Epub 2008 Sep 26.

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 EF 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 difficult to reconcile with a competing order parameter, but is consistent with pairing without condensation.