Crystal structure, phase diagram, electronic, magnetic and superconducting properties of AFe2-xMxAs2 -a joint experimental and theoretical study

本项目结合固体化学和固体物理的方法，将最近发现的铁离子超导体的实验研究和理论研究结合起来。建议的研究重点是AFe2-x MxAs2 （A= Ca, Sr, Ba, Eu； M= Mn, Co, Ni, Ru, Rh, Ir）家族化合物，并将研究晶体结构，化学取代，掺杂，内外压与各自的电子，磁性和超导性能之间的关系。高质量的单晶样品将合成和仔细表征各种技术。除了自己的热力学和输运测量外，这些单晶将被SPP的其他参与者用于多种光谱测量（光学，NMR, μSR, Mößbauer, dHvA）。从头算电子结构计算将伴随实验研究的所有阶段，以获得基于微观的物理性质的理解，并指导新化合物的修饰。基于现实结构模型，能带结构结果将为进一步在不同近似水平上建模提供准确的输入（相关轨道和耦合、DOS、费米曲面）。从带结构结果与实验数据的比较中，我们期望对这些新型高温超导体的结构性质关系有基本的认识。

This project connects experimental investigations and theoretical studies of the recently discovered iron pnictide superconductors joining approaches from solid state chemistry and solid state physics. The suggested study focuses on the AFe2-x MxAs2 (A= Ca, Sr, Ba, Eu; M= Mn, Co, Ni, Ru, Rh, Ir) family of compounds and will investigate the relation between crystal structure, chemical substitution, doping, internal as well as external pressure and the respective electronic, magnetic and superconducting properties. High quality single crystalline samples will be synthesized and carefully characterized by various techniques. In addition to own thermodynamic and transport measurements, these single crystals will be used by other participants of the SPP for a multitude of spectroscopic measurements (optics, NMR, μSR, Mößbauer, dHvA). Ab initio electronic structure calculations will accompany the experimental studies in all stages to obtain a microscopically based understanding of the physical properties and guide the modification of new compounds. Based on realistic structural models, the band structure results will provide accurate input (relevant orbitals and couplings, DOS, Fermi surfaces) for further modelling on different levels of approximation. From the comparison of the band structure results with the experimental data we expect fundamental insights in the structure property relations of these new high temperature superconductors.