Complete renormalization group calculation up to two-loop order of an effective two-band model for iron-based superconductors

Abstract

We perform a renormalization group (RG) study up to two-loop order of an effective low-energy two-band model to describe some of the recently discovered iron-based superconductors. Our starting point is the itinerant electronic model proposed by Chubukov et al.(Phys. Rev. B, 78 (2008) 134512), which displays two small, almost nested Fermi pockets with one hole pocket centered at (0,0) and one electron pocket centered at Q =(π, π) in the folded Brillouin zone. We then proceed to implement a complete two-loop RG calculation for this model of four-point vertex corrections, quasiparticle weight and several order parameter susceptibilities in order to evaluate the robustness of one-loop RG results available in the literature with respect to including self-energy effects and higher-order quantum fluctuations.