Evidence for granularity, anisotropy and lattice distortions in cuprate superconductors and their implications

Physik-Institut der Universit¨at Zu¨rich, Winterthurerstrasse 190, CH-8057, SwitzerlandGranularity, anisotropy, local lattice distortions and their dependence on dopant concentrationappear to be present in all cuprate superconductors, interwoven with the microscopic mechanismsresponsible for superconductivity. Here we review anisotropy and penetration depth measurementsto reassess the evidence for granularity, as revealed by the notorious rounded phase transition, theevidence for the three dimensional nature of superconductivity, uncovered by the doping depen-dence of transition temperature and anisotropy, and to reassess the relevance of the electron-latticecoupling, emerging from the oxygen isotope effects.