Regensburg 2010 – wissenschaftliches Programm
TT 24.1: Vortrag
Mittwoch, 24. März 2010, 14:00–14:15, H19
Tight-binding parameterization of the O-doped high-temperature superconductor Bi2Sr2CaCu2O8+δ — •Kateryna Foyevtsova1, Hai Ping2, Hem Kandpal1, Harald Jeschke1, Roser Valenti1, and Peter Hirschfeld2 — 1Institut für Theoretische Physik, Goethe-Universität Frankfurt, 60438 Frankfurt am Main, Germany — 2University of Florida, Gainesville, Florida 32611, USA
Recent scanning tunneling microscopy studies of several hole-doped high-Tc cuprate superconductors reveal a positive correlation between the position of a dopant atom and the size of local superconducting gap. These findings can be explained in the framework of spin exchange mediated pairing theories of superconductivity in cuprates, provided that in the parent compound certain modifications of local electronic structure occur due to a dopant, which has been so far neither proved nor disproved.
We present a Density Functional Theory study on oxygen-doped Bi2Sr2CaCu2O8+δ aimed at gaining insight into the dopant-induced variations of electronic structure of this high-Tc superconductor. In our study, we develop a method to characterize the Bi2Sr2CaCu2O8+δ bandstructure in terms of a single-band tight-binding (TB) Hamiltonian. We present three alternative TB models and critically discuss the achievements and drawbacks of the proposed approach. The discussion is supplemented by comparison of the spin susceptibilities and the pairing strengths calculated in the random-phase approximation from the derived TB models.