Electronic structure studies of the Bi2212 system by polarised X-ray absorption measurement

Polarised X-ray absorption (XAS) measurements have been made on high-quality superconducting Bi2Sr2CaCu2Os+y (Bi2212) single crystals to investigate the microscopic electronic structure in the normal and superconducting state of the system. The Cu L 3 XAS results led us to conclude that either there are no holes of 3dzz symmetry, or if any, they are insignificant in number. On the other hand, the O K XAS results show the presence of a significant density of p~ symmetry orbitals for itinerant holes. An increase in the 3d9_L/3d 9 ratio estimated from the Cu L 3 XAS measurements was observed while going from the normal to the superconducting state of the system. The results are discussed in the light of the structural distortions taking place below T c.