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TT: Fachverband Tiefe Temperaturen

TT 15: Superconductivity: Poster Session

TT 15.12: Poster

Dienstag, 26. Februar 2008, 14:00–18:00, Poster B

Magic doping fractions in Bi2201 — •Lenart Dudy, Alica Krapf, Beate Müller, Olaf Lübben, Helmut Dwelk, Christoph Janowitz, and Recardo Manzke — Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr.15, D-12489 Berlin, Germany

One interesting feature in the hole doped cuprates is the depression of the superconducting transition temperature at certain hole doping fractions. The 1/8 depression in La_2−xSr_xCuO₄(LSCO) [1] is widely accepted, and can be interpreted in terms of static stripes [2] - but also by a structural tetragonal-orthorhombic (LTT-LTO) phase transition [3]. In our view the structural interpretation can be ruled out, as additional to 1/8 other fractional depressions were deduced for LSCO (i.e. at 1/16; 3/32; 1/8; 3/16 ) [4]. But these fractions may also violate the stripe picture, as they can not be interpreted by a static one-dimensional arrangement of holes in the CuO₂-plane but by a two-dimensional one. Despite one controversial report [5] in the Bismuth cuprates the knowledge of the existence or non existence of such fractions is very poor. We will show that also in the one-layer Bismuth cuprate the depressions at certain hole doping fractions exist which are equal to the fractions found by [4]. This may point to a generality of magic doping fractions in the cuprates.

[1] A. R. Moodenbaugh et al., Phys. Rev. B 38, 4596 (1988)

[2] D.L. Feng et al., Journ. of Phys. and Chem. of Solids 67, 198 (2006)

[3] J. Zhao et al., Supercond. Sci. Technol. 18, 966 (2005)

[4] S. Komiya et al., Phys. Rev. Lett. 94, 207004 (2005)

[5] W.L. Yang et al., Phys. Rev. B 62, 1361 (2000) 1