Interplay between Magnetism, Superconductivity, and Orbital Order in 5-Pocket Model for Iron-Based Superconductors: Parquet Renormalization Group Study.
We report the results of the parquet renormalization group (RG) analysis of the phase diagram of the most general 5-pocket model for Fe-based superconductors. We use as an input the orbital structure of excitations near the five pockets made out of d_{xz}, d_{yz}, and d_{xy} orbitals and argue that there are 40 different interactions between low-energy fermions in the orbital basis. All interactions flow under the RG, as one progressively integrates out fermions with higher energies. We find that the low-energy behavior is amazingly simple, despite the large number of interactions. Namely, at low energies the full 5-pocket model effectively reduces either to a 3-pocket model made of one d_{xy} hole pocket and two electron pockets or a 4-pocket model made of two d_{xz}/d_{yz} hole pockets and two electron pockets. The leading instability in the effective 4-pocket model is a spontaneous orbital (nematic) order, followed by s^{+-} superconductivity. In the effective 3-pocket model, orbital fluctuations are weaker, and the system develops either s^{+-} superconductivity or a stripe spin-density wave. In the latter case, nematicity is induced by composite spin fluctuations.
Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany.|School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Laura
L
Classen
School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Rui-Qi
RQ
Xing
Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA.|Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
Maxim
M
Khodas
School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Andrey V
AV
Chubukov