Spin and superconducting fluctuations in the copper-oxygen planes of a quasi-two-dimensional high-temperature superconductor

The features of the two-dimensional superconducting and spin fluctuations i n the copper-oxygen planes of quasi-two-dimensional high-T-c superconductor s at T <T*, where T* is the charge ordering temperature, are studied in the two-dimensional (2D) XY model of Berezinskii, Kosterlitz, and Thouless. It is shown that the coexistence of three phases (metallic, almost insulating , and superconducting) in the copper-oxygen planes, with an independent dis tribution in each plane, enhances the semiconductor character of the charge transport along the (c) over cap axis and leads to two channels of charge tunneling with different temperature dependence of the tunneling probabilit y t(c)(T). The expressions obtained for the temperature dependence of the r esistivity rho (c)(T) can be used to determine the temperature of the 2D XY ordering of the copper spins in the insulating stripes and the dimensional ity of the superconducting transition from the results of measurements. (C) 2001 American Institute of Physics.