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Iron-pnictides: A brief introduction, effective low- energy models and RPA results
George Martins (Oakland University, USA)
03.06.2011 at 10:15
In this talk, a brief introduction to experimental and theoretical results for the iron pnictides
will be given, trying to compare its similarities and differences with the cuprates. The pnictides
parent compound, in all the families of superconducting pnictides known, is a semimetal with an
Spin Density Wave (SDW) ground state, which under doping, for some families, and under
pressure for others, becomes superconducting (max T_c ~ 56 K).
The model of choice has been a 5-band Hubbard model, with longer than nearest-neighbor tight
binding hoppings and some on-site correlation terms (although I will argue that efforts to work
with a 2-band model should be pursued). An RPA solution to this model will be presented for the
spin susceptibility and the pairing function. It will be argued that the extreme richness of the
Fermi surface (coming from all the hybridized d-states) results in RPA solutions which are very
dependent on the tight binding hopping terms and in a ‘fierce’ competition between different
symmetries for the pairing function. This may be one of the important differences in relation to
the cuprates.
A348 Theresienstr.37