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TT: Tiefe Temperaturen

TT 15: Superconductivity - Properties, Electronic Structure, Order Parameter I

TT 15.5: Talk

Saturday, March 5, 2005, 15:00–15:15, TU H2053

Determination of the hole density of (Bi,Pb)₂(Sr,La)₂CuO_6+δ superconductors — •L. Lasogga¹, R. Mitdank¹, A. Krapf¹, H. Dwelk¹, S. Rogaschewski¹, C. Janowitz¹, R. Manzke¹, K. Scheurell², and I. Murwani² — ¹Humboldt University Berlin, Department of Physics, Newtonstrasse 15, 12489 Berlin — ²Humboldt University Berlin, Department of Chemistry, Brook-Taylor-Strasse 2, 12489 Berlin

The hole concentration of the CuO₂ planes of Bi_2−yPb_ySr_2−xLa_xCuO_6+δ cuprates has been investigated in great detail by two techniques, x-ray absorption spectroscopy (XAS) at the Cu−L₃ edge and iodometric titration. The XAS measurements were performed at the BESSY II beamline PM3. Our investigations include both ceramics and single crystals containing no lead (y = 0) and larger amounts of lead (y = 0,16 ... 0,45). For each case we studied series of variable content of lanthanum (x = 0,0 ... 0,8). Finally we compare ceramics and single crystals, discuss the dependence between hole density, critical temperature and content of lead and lanthanum. Moreover we show the dependence of the x-ray absorption from the angle of incidence.