title: Electronic structure and superconductivity of FeSe-related superconductors.
abstract: 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.
authors.affiliation: 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.
authors.forename: Xu
authors.initials: X
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.forename: Shaolong
authors.initials: S
authors.lastname: He
authors.forename: Junfeng
authors.initials: J
authors.lastname: He
authors.forename: Defa
authors.initials: D
authors.lastname: Liu
authors.forename: Daixiang
authors.initials: D
authors.lastname: Mou
authors.forename: Bing
authors.initials: B
authors.lastname: Shen
authors.forename: Yong
authors.initials: Y
authors.lastname: Hu
authors.forename: Jianwei
authors.initials: J
authors.lastname: Huang
authors.forename: X J
authors.initials: XJ
authors.lastname: Zhou