Inhomogeneous superconductivity and the "pseudogap state of novel   superconductors
  Novel superconducting compounds such as the high Tc oxides are intrinsically inhomogeneous systems. An inhomogeneous structure is created by doping and the statistical nature of the distribution of dopants. Consequently, the critical temperature is spatially dependent: Tc = Tc (r). 
Vladimir Kresin, Yurii N. Ovchinikov and Stuart A. Wolf