X-ray diffuse scattering experiments from bismuth based high T$_c$ superconductors

A detailed X-ray diffuse scattering study of the recently found two dimensional (2D) displacive short range order (SRO) superstructure, with doubled periodicity along the orthorhombic a direction from the high T$_c$ superconductors Bi$_2$Sr$_2 $CaCu$_2$O$_{8+\delta}$(BISCO-2212) is reported. The investigation has been extended to high and low temperatures for optimally doped crystals, to crystals with different doping levels and to the one layer compound Bi$_2$Sr$_2$CaCuO$_ {6+\delta}$ (Bi-2201). The most striking feature is that both, the intensity of the diffuse scattering and the extent of the 2DSRO vary with doping as the critical temperature, T$_c$. These findings show that these short range ordering features are of importance for a better understanding of high Tc materials, at least those from the BISCO family.