Anisotropic superconducting and normal state transport properties of HTSC single crystals

This paper discusses the common feature of layered crystal structures in the family of high temperature superconductors (HTSCs), including La-Ba(Sr)-Cu- O, Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O. The author discusses the general belief that the two-dimensional CuO2 network is the most essential building block of the high Tc materials. A notable exception is the recently discovered Bi-K-Ba-O system, a 30 K class superconductor with a cubic perovskite structure. As the anistropy is the main theme of this chapter, the discussion will be focused upon the cuprate HTSCs. One expects the quasi-two-dimensionality associated with the layered crystal structures to be manifested in various aspects of HTSCs, i.e. not only in the superconducting properties but also in the electronic, thermal, optical and mechanical properties in the normal state