Tunneling spectroscopy of the Superconductor-Insulator Transition on Bi2Sr2Ca1−xYxCu2O8+δ and (Bi1−yPby)2Sr2Ca1−xYxCu2O8+δ

The purpose of our present study is to understand the Superconductor-Insulator Transition. In this paper we report tunnel experiments on Bi 2 Sr 2 Ca 1-x Y x Cu 2 O 8+δ (Y-Bi2212) crystals with x = 0, 0.01, 0.05, 0.1, 0.11 and 0.12. The results are discussed about Copper pairs existing. Tunneling spectra were measured for Y-Bi2212 crystal-SiO-Ag planar junctions. For superconducting samples the V-shape gap structure and zero bias conductance peaks (ZBCP) were observed. While neither superconducting gap nor ZBCP was observed for insulating samples. These results suggest that Cooper pairs break up on the insulating side of SIT. In our spectra there were also several characteristic behaviors.