Some Consequences of the Layered Structure of HTSC

A. A. Abrikosov

《Chinese Journal of Physics》 34卷2S期 (1996/04) Pp. 330-339

並列摘要

The S-N model for high Tc superconductors is briefly described and some inadequacy is mentioned for HTSC containing no CuO chains between the CuO2 planes. A theory is presented for the static c-axis conductivity and superconductivity for such superconductors and compared with experimental data on YBCO with varying oxygen concentration. The basis is the assumption that the hopping of electrons between the CuO2 planes is due to resonant tunneling through localized centers between the planes, and the amplitudes for different centers having the same energy are coherent. The dependence of the normal conductivity on temperature and concentration of resonant centers is calculated. Comparison with experiment shows reasonable agreement. From the obtained dependence of the concentration of resonant centers on the oxygen concentration it can be concluded that these centers disappear simultaneously with holes in the valence band, and hence both originate from the same impurity states with energies below the top of the valence band, which disappear at a certain doping. The supercurrent in the superconducting state proves to be of the Josephson type. The critical value is defined as function of temperature and concentration of resonant centers. Its magnitude is estimated to be Jc～10^5 -10^7 A/cm^2.