Electron selfenergy in the superconducting pnictides:orbital dependence, anisotropy, temperature dependence and its relation with the phase diagram

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This project aims at a theoretical description of the electronic self-energy due to short-ranged electron-electron interactions in multi-band models for the iron pnictide superconductors. The primary objects of interest are the wave-vector, orbital/ band and temperature dependences of the normal-state self-energy around the various Fermi pockets. The orbital dependence of the self-energy has a direct influence on the predicted superconducting gap structure around the Fermi pockets and hence on the whole phase diagram. Its inclusion is therefore an important step to assure the predictive power of the weak-coupling theory for the gap structure. Furthermore, motivated by experimental trends in the resistivity, the relation of possible non-Fermi-liquid-like components in the imaginary part of the self-energy to the critical temperature for superconductivity, Tc, or other phase transition lines, will be investigated. Here, besides the trends as a function of doping, the evolution of the self-energies and Tcs as a function of pressure will be computed as a cross check. The goals are the comparison with the experimental findings for the relation between resistivity and Tc and to predict experimental signatures that can be used to discriminate between different theoretical ideas for the superconducting pairing. The main theoretical method used is the functional renormalization group, but other techniques like the random phase approximation and Boltzmann transport equations may be used as well for further modelling and comparison.