Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity: Cuprate High-Temperature Superconductors 2
TT 30.4: Vortrag
Mittwoch, 25. März 2009, 14:45–15:00, HSZ 304
Effect of dopant atoms on local superexchange in cuprate superconductors: a perturbative treatment — •Kateryna Foyevtsova1, Roser Valenti1, and Peter Hirschfeld2 — 1Institut für Theoretische Physik, Goethe-Universität Frankfurt, 60438 Frankfurt am Main, Germany — 2University of Florida, Gainesville, FL 32611, USA
On the basis of the three-band Hubbard model for the cuprates, we calculate the magnetic superexchange between Cu ions in the presence of dopants up to fifth-order in perturbation theory. We find that fourth- and fifth-order contributions are equally important, and demonstrate that their sign depends on the relative dopant-induced spatial variation of the atomic levels in the CuO2 plane, contrary to results obtained within the one-band Hubbard model. We discuss some realistic cases and their relevance for the pairing mechanism in the cuprate superconductors.