Local structure and Tc suppression in Bi2Sr2Cal_xYx(CUl_yZny)208,6 superconductor at 118 doping

Local structural studies on the Bi2Sr2Cal.xYx(CUl.yZny)208+ 5 superconductor have been carded out by Cu K-edge X-ray absorption spectroscopy. The Cu K-edge XANES spectra show a systematic evolution with the hole doping for y=0.0 while there is anomalous relaxation of the Cut 2 plane in the underdoped regime for y=0.025. Our results suggest that the 1/8 doping is a special doping below which the local structure of the Cut 2 plane shows strong sensitivity to extrinsic effects. The XANES features, associated with local structural distortions of the Cut 2 plane are discussed.