Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Superconductivity & Solids At Low Temperature - Poster Session

TT 7.32: Poster

Montag, 27. März 2006, 14:00–17:45, P1

Azimuthal polarization dependence of x-ray absorption of Bi-2201 single crystals — •B. Müller, R. Mitdank, L. Dudy, J. Rasch, B. Ziegler, L. Lasogga, H. Dwelk, A. Krapf, C. Janowitz, and R. Manzke — Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin

The hole concentration in the CuO₂-planes is one of the most important parameters of high-Tc superconductors and x-ray absorption spectroscopy (XAS) is well known to be an excellent experimental tool for its determination. For polycrystalline ceramic materials this has been demonstrated by analysing the so-called pre-peak at the O1s−2p absorption line [1] and a satellite line at the Cu2p−3d transition [2]. Also the single-CuO₂ layer superconductor Bi-2201 has been studied recently [3].

For single crystalline superconductors, on the other hand, likewise analyses gave completely non-systematic results. The reason for such an unexpected behavior is a distinct dependence of the absorption on the azimuthal polarization of the synchrotron radiation. A strong dependence on the polarization vector parallel and perpendicular to the surface is well known [1], but a dependence on orientation within the CuO₂-plane has not been considered so far.

[1] J. Fink et. al., Springer Series in Solid-State Sciences Vol. 91, 406 (1989)

[2] A.Q. Pham et. al., Phys. Rev. B 48, 1249 (1993)

[3] M. Schneider et. al., Phys. Rev. B 72, 014504 (2005)