ELECTRONIC-STRUCTURE STUDIES OF THE BI2212 SYSTEM BY POLARIZED X-RAY-ABSORPTION MEASUREMENT

Polarised X-ray absorption (XAS) measurements have been made on high-q uality superconducting Bi2Sr2CaCu2O8+y (Bi2212) single crystals to inv estigate the microscopic electronic structure in the normal and superc onducting state of the system. The Cu L(3) XAS results led us to concl ude that either there are no holes of 3d(z)2 symmetry, or if any, they are insignificant in number. On the other hand, the O K XAS results s how the presence of a significant density of p(z) symmetry orbitals fo r itinerant holes. An increase in the 3d(9)L/3d(9) ratio estimated fro m the Cu L(3) XAS measurements was observed while going from the norma l to the superconducting state of the system. The results are discusse d in the light of the structural distortions taking place below T-c.