Enhanced Josephson tunneling between high temperature superconductors   through a normal pseudogap underdoped cuprate with a finite energy cooperon
  The Josephson coupling between optimally cuprate superconductors separated by a spacer with a finite energy cooperon excitation which contributes to the Josephson coupling strength, is examined. For an underdoped cuprate barrier in its normal state, the YRZ model gives a good description of the temperature dependent enhanced Josephson coupling. A detailed examination of origin of the enhancement shows a significant contribution from the cooperon excitation which is comparable to that from nodal quasiparticles. 
Kun Huang, Wei-Qiang Chen, T. M. Rice, and F. C. Zhang
cond-mat.str-el cond-mat.supr-con