Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 32: SC: Fe-based Superconductors - Theory
TT 32.9: Talk
Wednesday, March 16, 2011, 12:45–13:00, HSZ 304
Antiferromagnetic order in multi-band Hubbard models for iron-pnictides — •Tobias Schickling1, Florian Gebhard1, and Jörg Bünemann2 — 1Fachbereich Physik, Philipps Universität, Renthof 6, 35032 Marburg — 2Institut für Physik, BTU Cottbus, Postfach 101344, 03013 Cottbus
In our presentation, we discuss the physics of multi-band Hubbard models for
La O Fe As which we have investigated by means of the Gutzwiller variational theory [1]. An
analysis of the paramagnetic ground state shows that neither Hartree–Fock mean-field theories nor effective spin models describe these systems adequately. In contrast to Hartree–Fock-type approaches, the Gutzwiller theory predicts that antiferromagnetic order requires substantial values of the local Hund’s-rule exchange interaction. For a three-band model, the antiferromagnetic moment fits experimental data for a broad range of interaction parameters. However, for the
more appropriate five-band model, the iron eg electrons polarize the t2g electrons and they substantially
contribute to the ordered moment. Therefore, we argue that an inclusion of the arsenic 4p bands is essential for
a proper description of the magnetic order in La O Fe As.
T. Schickling, F. Gebhard, and J. Bünemann, arXiv:1011.6219