ARPES of iron-based superconductors

100年前，人类学会了如何液化氦，这导致了在极低温度（~4K）下发现金属的超导性。几十年前发现的铜超导体在相对较高的温度下（高达~140K）会失去电阻，但与低温超导体不同的是，直到现在人们还没有完全了解铜超导体。到目前为止，新合成的砷化铁超导体的临界温度还不是很高（< 50 K），但工业潜力很大，因为主要成分是铁。本提案的目的是研究新型超导体的电子结构。将应用现代高分辨率角分辨光谱学的最新发展来研究一系列铁化合物。光发射光谱应该传递关于费米表面的尺寸、形状、拓扑结构和嵌套特性的信息；超导波和密度波能隙的振幅、各向异性和特性电子态的色散、对称性和费米速度；实部和虚部的自能、电荷磁化率和玻色子自由度的耦合强度。为了排除在某些情况下可能改变光电信号的任何与表面有关的因素，将采用现代计算方法来表征这种可能的影响。该提案的主要目标是研究低能电子动力学的这些方面，与其他团队获得的知识一起，优先计划将有助于理解铁化合物的高温超导机制。

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.