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We report the results of the full parquet renormalization group (pRG) analysis of the 5-pocket model for Fe-based superconductors (three hole pockets and two electron pockets). We depart from the low-energy orbital model and use as input the fact that excitations near all five pockets are made out of xz, yz, and xy d-orbitals. We argue, based on symmetry that there are 40 different coupling constants which describe the interactions between low-energy fermions and flow under pRG. The pRG analysis reveals four stable fixed trajectories. They can be grouped into two classes, where the 5-pocket model effectively reduces either to a 3-pocket or a 4-pocket one. We argue that in both cases superconductivity wins over SDW if all five Fermi energies are small and pRG runs over a wide energy range. The resulting superconducting symmetry is ! of s+- fo r m for both effective models, but the magnitude of the gap differs between the hole pockets at (0,0) and (pi,pi) in the 1Fe zone. SDW magnetism is of stripe type in the 3-pocket and of checkerboard type in the 4-pocket case. Additionally a spontaneous orbital order develops before superconductivity that splits the band degeneracy at high-symmetry points.

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Laura Classen, University of Heidelberg
Seminar room 0.03, ETP
Contact: not specified