HOLE DENSITY AS SEEN BY XAS AND T-CS IN THE LAYERED SUPERCONDUCTING COPPER OXIDES

Thin films of a layered thallium cuprate have been studied by XAS at C u L(3)-edge in normal incidence in order to estimate the doping hole d ensities nh in the [CuO2](infinity) planes of the Tl(2212) structure. When going from as-synthesized samples to post-annealed ones under Ar, a decrease of the doping hole densities has been observed which corre sponds to an increase of T-c's. In order to evaluate the surface effec ts on the results, the absorption has been recorded simultaneously in total electron yield (TY) and fluorescence yield (FY) modes. After ful l correction of the self-absorption of the soft X-ray fluorescence pho ton, the estimated doping hole densities appeared to be in good agreem ent whatever the detection method.