Inhomogeneous Superconducting State and intrinsic Tc : Near Room Temperature Superconductivity in the Cuprates

Doped cuprates are inhomogeneous superconductors. The concept of an intrinsic critical temperature, Tcintr.$equiv$ Tc*, whose value greatly exceeds that for the resistive Tcres.$equiv$ Tc, is supported by a number of experimental studies, including those performed recently. These data are discussed in this review. The anomalous diamagnetism observed at Tcres.$equiv$ <T< Tc* is a manifestation of the presence of superconducting clusters embedded into a normal metallic matrix. The value of intrinsic critical temperature in some cuprates reaches a value which is close to room temperature. The a.c. properties of such inhomogeneous systems are discussed.