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, T-intr.(c) equivalent to T-c*, whose value greatly exceeds that for the resistive T-res.(c) equivalent to 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 T-res.(c) < T < T-c* 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.