The electronic properties of cuprate ladder materials

We review the electronic properties of cuprate ladder materials, with a foc us on so called 'telephone number compound' (Sr, Ca)(14)Cu24O41. This is th e only ladder material which allows carrier doping and growth of single cry stals. These features made investigations possible of transport anisotropy and frequency-dependent (optical) conductivity. One of the remarkable disco veries is the realization of superconductivity under high-pressure; however , analysis of transport dimensionality has suggested that the superconducti vity is not due to Bose-Einstein condensation of singlet preformed pairs on the rungs, but due to cross-over from one- to two-dimensional electronic t ransport under pressure. This characterizes the superconductivity of 14-24- 41 compound to be 'anisotropic 2-d', an extension of the category where hig h T-c cuprates belong to. (C) 2001 Elsevier Science B.V. All rights reserve d.