铁基超导体的远红外光谱学研究

Infrared study of the iron-based superconductors

铁基超导体是由日本科学家Hosono发现的具有层状结构和多带特征的非常规超导体,虽然人们利用各种实验手段对不同家族的铁基超导体进行了详尽的研究,最受关注的超导机理的问题尚未解决,也吸引着人们进行更加深入的探索.红外光谱是研究费米面附近的电子态激发以及晶格振动动力学的重要实验探测手段,在早期的超导研究中对于超导能隙的确定和电声相互作用的探测起到了重要作用.本文将主要介绍近些年国际上利用傅里叶变换红外光谱学研究铁基超导体方面的主要进展,并结合作者近些年的工作详细地阐述红外光谱的具体应用,主要包括以下几个方面的内容:(1)铁基超导体中的超导能隙;(2)(Ba,K)Fe_2As_2中的量子临界与非费米液体行为;(3)KFe_2As_2中的轨道选择性行为;(4)铁基超导材料中的电声相互作用;(5)铁基超导材料中的向列相.最后,在总结已有工作的基础上,我们对未来红外光谱在铁基超导材料中的研究做了进一步的展望.

Iron-based superconductors are discovered by Japanese scientists Hosono, which have layered structures and characterized by multi-orbital nature. Although a large amount of investigations have been done with different experimental techniques on various families of iron-based superconductors, the most important issue concerning the superconducting mechanism remains controversial, and much more efforts need to be done in order to resolve this issue.Infrared spectroscopy is an important technique to study the electron excitations near the Fermi surface and lattice dynamics in condensed matter, it has played an important role in the early studies of superconductivity in determining the superconducting gaps and electron-phonon couplings. In this paper, we first make a brief introduction to the experimental techniques of infrared spectroscopy, and then we review some recent progress in the investigation of iron-based superconductors with infrared optical spectroscopy. The content includes：（1） superconducting gap in iron-based superconductors;（2） quantum critical and non-Fermi-liquid behavior in（Ba,K）Fe2As2;（3） orbital-selective physics in KFe2As2;（4） lattice dynamics, and（5） nematicity in iron-based superconductors. At last, we summarize what can be further explored by infrared spectroscopy in understanding of superconducting mechanism in iron-based superconductors.