Polarized XANES Study of Cu L3 Edges of Bi-2212 Superconducting Single crystals Using Total and Fluorescence Yield Techniques

XANES with polarized synchrotron light is now established to be one of the important techniques for the study of the electronic structure of high-T-c superconductors in order to find out the symmetry of holes and their implication to the theoretical models proposed to explain superconductivity in these cuprates. The XANES spectra are measured by two methods in the soft X-ray region, namely, total yield (TY) and fluorescence yield (FY) methods, which give different results with respect to out-of-plane Cu 3d(z(2)) symmetric holes. The reason of this discrepancy is not quite clear. Polarized XANES measurements on Bi-2212 single crystals at the Cu L(3) edge by the TY and FY methods are reported and the results are discussed in detail.