Tunneling Spectroscopy Of The Superconductor-Insulator Transition On Bi2sr2ca1-Xyxcu2o8+Delta And (Bi1-Ypby)(2)Sr2ca1-Xyxcu2o8+Delta

We report tunnel experiments on Bi2Sr2Ca1-xYxCu 2O8+delta (Y-Bi2212) crystals with x= 0, 0.01, 0.05, 0.1, 0.11, and 0.12. The results are discussed about Cooper pairs existing. Tunneling spectra were measured for Y-Bi2212 crystal-SiO-Ag planar junctions. For superconducting samples the V-shaped gap structure and zero bias conductance peaks (ZBCP) were observed. While neither superconducting gap nor ZBCP was observed for insulator samples. These results suggest that Cooper pairs break up on the insulating side of superconductor- insulator transition (SIT). We also measured tunneling spectra on (Bi1-Pb-y(y))(2)Sr2Ca1-xYxCu2O8+delta samples. In their spectra there were also several characteristic behaviors.