Liu Xu, Zhao Lin, He Shaolong, He Junfeng, Liu Defa, Mou Daixiang, Shen Bing, Hu Yong, Huang Jianwei, Zhou X J
National Lab for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
J Phys Condens Matter. 2015 May 13;27(18):183201. doi: 10.1088/0953-8984/27/18/183201. Epub 2015 Apr 16.
FeSe superconductors and their related systems have attracted much attention in the study of iron-based superconductors owing to their simple crystal structure and peculiar electronic and physical properties. The bulk FeSe superconductor has a superconducting transition temperature (Tc) of ~8 K and it can be dramatically enhanced to 37 K at high pressure. On the other hand, its cousin system, FeTe, possesses a unique antiferromagnetic ground state but is non-superconducting. Substitution of Se with Te in the FeSe superconductor results in an enhancement of Tc up to 14.5 K and superconductivity can persist over a large composition range in the Fe(Se,Te) system. Intercalation of the FeSe superconductor leads to the discovery of the AxFe2-ySe2 (A = K, Cs and Tl) system that exhibits a Tc higher than 30 K and a unique electronic structure of the superconducting phase. A recent report of possible high temperature superconductivity in single-layer FeSe/SrTiO3 films with a Tc above 65 K has generated much excitement in the community. This pioneering work opens a door for interface superconductivity to explore for high Tc superconductors. The distinct electronic structure and superconducting gap, layer-dependent behavior and insulator-superconductor transition of the FeSe/SrTiO3 films provide critical information in understanding the superconductivity mechanism of iron-based superconductors. In this paper, we present a brief review of the investigation of the electronic structure and superconductivity of the FeSe superconductor and related systems, with a particular focus on the FeSe films.
FeSe 超导体及其相关体系因其简单的晶体结构以及独特的电子和物理性质，在铁基超导体的研究中备受关注。块状 FeSe 超导体的超导转变温度（Tc）约为 8 K，在高压下可显著提高至 37 K。另一方面，其同族体系 FeTe 具有独特的反铁磁基态，但不超导。在 FeSe 超导体中用 Te 替代 Se 会使 Tc 提高至 14.5 K，并且在 Fe(Se,Te) 体系的较大成分范围内超导性都能持续存在。FeSe 超导体的插层导致发现了 AxFe2-ySe2（A = K、Cs 和 Tl）体系，该体系表现出高于 30 K 的 Tc 以及超导相独特的电子结构。最近关于单层 FeSe/SrTiO3 薄膜中可能存在 Tc 高于 65 K 的高温超导性的报道在该领域引起了极大的轰动。这项开创性的工作为探索高温超导体的界面超导性打开了一扇门。FeSe/SrTiO3 薄膜独特的电子结构和超导能隙、层依赖行为以及绝缘体 - 超导体转变为理解铁基超导体的超导机制提供了关键信息。在本文中，我们简要回顾 FeSe 超导体及其相关体系的电子结构和超导性的研究，特别关注 FeSe 薄膜。
