ABSTRACT

Despite more than ten years of extensive research, the superconducting mechanism of iron-based superconductors (FeSCs) is still an open question. Generally, the high-temperature superconductivity is often observed with suppression of magnetic ordering, spin-density-wave, or even the structure transition by carrier doping. Furthermore, an electronic state ordering is also observed at temperatures close to or even above these transitions. Due to its proximity to the superconducting state and disappearance near the optimal superconductivity, it has been also suggested to interplay with superconductivity on a phenomenological level. Nevertheless, there is still no direct evidence to bridge the superconductivity to these transitions. Recently, another nematic order was observed in the superconducting state of heavily hole-doped compound AFe${ }_2$As${ }_2$ (A = K, Rb, Cs), providing a possibility to explore the superconductivity gap symmetry nature. Here, by reviewing the recent experimental progresses on the nematic superconductivity in the FeSCs, we will introduce the progresses by various methods including the quasi-particle interference from scanning tunneling microscope, anisotropic gap magnitudes from angular resolved photoemission, the upper critical field and the superconducting transition temperatures from transport measurements. In addition, some recent reports and theoretical explanations for experimental results are followed.

摘要

尽管进行了十多年的广泛研究，但铁基超导体（FeSCs）的超导机理仍然是一个悬而未决的问题。通常，高温超导现象通常在通过抑制载流子掺杂而抑制磁有序，自旋密度波甚至结构转变的过程中观察到。此外，在接近或什至高于这些转变的温度下也观察到电子状态排序。由于它靠近超导状态，并且在最佳超导性附近消失，因此，它也被认为在现象学层面上与超导相互作用。然而，仍然没有直接证据将超导性桥接到这些转变。最近，在重掺杂空穴的化合物AFe的超导状态下观察到另一个向列顺序${ }_{\mathrm{2个}}$作为${ }_{\mathrm{2个}}$（A = K，Rb，Cs），为探索超导间隙对称性质提供了可能性。在此，通过回顾FeSCs的向列超导性的最新实验进展，我们将介绍各种方法的进展，包括扫描隧道显微镜产生的准粒子干涉，角分辨光发射的各向异性间隙幅度，上临界场和超导。运输测量得出的转变温度。此外，还遵循了一些有关实验结果的最新报道和理论解释。