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

本项目旨在从理论上描述铁锂超导体多能带模型中短程电子-电子相互作用所产生的电子自能。主要感兴趣的对象是各种费米口袋周围的正常态自能的波矢、轨道/带和温度的依赖关系。自能的轨道依赖性直接影响到预测的费米口袋周围的超导能隙结构，从而影响整个相图。因此，它的包含是确保弱耦合理论对间隙结构的预测能力的重要一步。此外，在实验趋势的推动下，还将研究自能虚部中可能的类费米液体成分与超导临界温度T_c或其他相变线的关系。这里，除了作为掺杂函数的趋势外，还将计算作为压力函数的自能和TCS的演变作为交叉检查。其目的是将电阻率与T_c之间的关系与实验结果进行比较，并预测可用于区分超导对的不同理论观点的实验特征。使用的主要理论方法是泛函重整化群，但也可以使用其他技术，如随机相位近似和玻尔兹曼输运方程来进行进一步的模拟和比较。

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.