Dresden 2009 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 36: Focussed Session: Superconductivity and Magnetism in Ferropnictides and Related Materials
TT 36.5: Talk
Thursday, March 26, 2009, 11:45–12:00, HSZ 03
DFT studies of Iron-based Superconductors — •Lilia Boeri1, Oleg V. Dolgov1, Alexander A. Golubov2, and Ole Krogh Andersen1 — 1MPI-FKF, Heisenbergstrasse 1, D-70569 Stuttgart, Germany — 2Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente,7500 AE Enschede, The Netherlands
The discovery of superconductivity in iron pnicticides has generated considerable interest. So far, however, not only the pairing mechanism, but even the basic electronic structure of these materials is not well understood.
We use Density Functional Theory to understand the electronic and vibrational properties of LaOFeAs, which can be considered a prototype for iron pnictides.
First, we calculate the phonon dispersions and electron-phonon coupling using linear response and show that standard Migdal-Eliashberg theory cannot explain the experimental Tc. Then we derive ab-initio an accurate tight-binding Hamiltonian, using downfolding + N-ization (NMTO), which allows us to elucidate the origin of the complicated band structure of iron pnicticides. As a first application of our model, we study itinerant magnetism.