Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 24: Postersitzung III: Korrelierte Elektronen, ”Orbital Physics”

TT 24.23: Poster

Mittwoch, 10. März 2004, 14:30–19:00, Poster A

Electronic structure, magnetism, and superconductivity in pseudo-ladder compounds — •S.-L. Drechsler¹, H. Rosner¹, N.M. Plakida², A. Vladimirov³, H. Eschrig¹, and M. Knupfer¹ — ¹IFW-Dresden, P.O. Box 270116, 01171 Dresden, Germany — ²MPI-CPfS Dresden, Germany — ³J. Inst. f. Nuclear Res., Dubna, Russia

The electronic structure of ACu₂O₃ compounds [A=Ca,Mg] has been calculated within the local density approximation and compared with x-ray absorption spectroscopy and magnetic neutron scattering data [1]. Both compounds deviate markedly from the usual pdσ cuprate picture. Significant interlayer exchange in the stacking c-direction is found to be responsible for the missing spin gap (generic for ideal two-leg ladders) and the finite Néel-temperature. Hence, they can be modelled as weakly coupled anisotropic Heisenberg (Hubbard) bi-layers. Within a derived effective t-J-model in mean-field approximation nodeless superconductivity below 50 K is predicted for Ca_0.88Na_0.12Cu₂O₃ (optimal hole doping).

[1]V. Kiryukhin et al., PRB 64, 1444418 (2001).