Pseudogap and transport in HTS

Perpendicular transport is one of the key factors to HTS superconductivity, sampling the quasi-insulating blocking layer, separating the conducting Cu O-planes, and driving the metal-insulator transition (MIT) that is induced by disorder and underdoping. Various measurements have been carried out to study the transport, the MIT, and the in-plane Fermi surface especially by surface methods via the blocking layer, and these depend sensitively on sur face quality. ARXPS results on UHV cleaving show that at 300 K and 10(-10) Torr, a Bi hydroxide layer occurs in 30 min, followed by H2O or CyHxOH chem isorption. Consequences of this result on STS, ARPES, perpendicular transpo rt, Coulomb charging, and pseudogap are analyzed, yielding scenario for HTS superconductivity, where static and dynamic charge exchange via and with t he blocking layer initiates plaques of preformed pairs of d-wave symmetry w eakening the inplane Coulomb repulsion yielding by this plasmonic mechanism , finally, HTS. Consequences of this scenario on anisotropic transport with its strong Fermi velocity nu (p) anisotropy and its strong in-plane scatte ring rate Gamma (II)(T) approximate to const. at (pi ,0) in k-space with ps eudo gap kT* approximate to Delta (p)/3 and superconducting gap Delta (S) a pproximate to 3 kT(C) maxima and the strongly decreasing rate Gamma (II)(T) alpha T at 0.4 (pi, pi) with pseudo gap Delta (p)(k) node and superconduct ing gap Delta (s)(k) node are given.