ELECTRONIC-STRUCTURE OF BI2CASR2CU2O8 DETERMINED BY A COMBINED ANALYSIS OF VARIOUS POLARIZED X-RAY-ABSORPTION SPECTRA

The polarized E perpendicular-to c oxygen K-edge x-ray-absorption near-edge structure (XANES) spectrum of Bi2Sr2CaCu2O8 + delta (Bi 2:2:1:2) has been calculated by a multiple-scattering approach and compared with experimental data. The symmetry of the conduction bands over a range of 15 eV above the Fermi level has been studied by a combined analysis of five different polarized x-ray-absorption spectra at the following edges: O K edge, Cu K edge, and Cu L3 edge. Information on the partial density of states of the conduction bands, D(x(l,m(l))), projected on the atomic site X (Cu and O) with selected orbital angular momentum l, and its projection m(l) along the c axis (D(Cu(2,0)), D(Cu(2, +/- 1)), and D(Cu(2, +/- 2)) for the Cu site; D(O(1,0)) and D(O(1, +/- 1)) for the oxygen site) have been obtained. The symmetry of the itinerant states induced by doping at the Fermi level is deduced to be a mixture of 3d holes with m(l) = +/- 2 and m(l) = 0 orbital angular momenta and holes on planar oxygen in the molecular-orbital combination of local b1 and a1 symmetry [the ligand holes L(b1) and L(a1)].