ARPES of iron-based superconductors

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100 years ago humanity learned how to liquify helium and this led to discovery of superconductivity in metals at very low temperatures (~4K). The cuprate superconductors, discovered a couple of decades ago, lose their resistance at relatively high temperatures (up to ~140K), but unlike their low-temperature counterparts remain not completely understood until now. The critical temperatures achieved so far in newly synthesized iron arsenide superconductors are not very high (< 50 K) but industrial potential is, since the main component is the iron. The aim of this proposal is to study the electronic structure of new superconductors. The latest developments of the modern high-resolution angle-resolved photoemission spectroscopy will be applied to investigate a series of iron pnictides. Photoemission spectroscopy should deliver the information about the size, shape, topology and the nesting properties of the Fermi surface; amplitude, anisotropy and character of the superconducting and density waves energy gaps; dispersion of the electronic states, their symmetry and Fermi velocity; real and imaginary parts of the self-energy, charge susceptibility and a coupling strength to bosonic degrees of freedom. In order to rule out any surface related factors which in some cases can modify photoemission signal the modern computational methods will be employed to characterize such possible influence. The main goal of the proposal is to investigate those aspects of the low energy electron dynamics, which together with the knowledge gained by other teams of the Priority Program will help to understand the mechanism of high-temperature superconductivity in iron pnictides.