We study the five-orbital Hubbard model including the charge quadrupole interaction for iron pnictides. Using the fluctuation-exchange approximation, orbital fluctuations evolve inversely proportional to the temperature, and therefore the resistivity shows linear or convex T dependence for a wide range of temperatures. We also analyze the Eliashberg gap equation, and show that an s-wave superconducting state without sign reversal (s ++-wave state) emerges when the orbital fluctuations dominate over the spin fluctuations. When both fluctuations are comparable, their competition gives rise to a nodal s-wave state. The present study offers us a unified explanation for both the normal and superconducting states.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Apr 9 2012|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics