Polarized Cu LIII absorption study of a Bi2Sr2CaCu2O8 single crystal.

The polarization dependence of the Cu {ital L}{sub III} absorption spectrum was measured on a Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystal with linearly polarized synchrotron radiation. The Cu {ital L}{sub III} absorption peak shows no energy difference between the {ital z} (3{ital d}{sub 3{ital z}}{sup 2-}{ital r2}) and the {ital x},{ital y}(3{ital d}{sub {ital x}}{sup 2-}{ital y2}) component, which is consistent with the electron-energy-loss study by Nuecker {ital et} {ital al}., but is different from the previous x-ray absorption studies by Bianconi {ital et} {ital al}. and Abbate {ital et} {ital al}. The relative intensity of the {ital z} component to the {ital x},{ital y} component was estimated to be less than 5%, suggesting a very small contribution of the Cu 3{ital d}{sub 3{ital z}}{sup 2-}{ital r2} orbital to the electronic structure in the vicinity of the Fermi level.