title: Interface-induced superconductivity and strain-dependent spin density waves in FeSe/SrTiO3 thin films.
abstract: The record superconducting transition temperature (T(c)) for the iron-based high-temperature superconductors (Fe-HTS) has long been 56 K. Recently, in single-layer FeSe films grown on SrTiO3 substrates, indications of a new record of 65 K have been reported. Using in situ photoemission measurements, we substantiate the presence of spin density waves (SDWs) in FeSe films--a key ingredient of Fe-HTS that was missed in FeSe before--and we find that this weakens with increased thickness or reduced strain. We demonstrate that the superconductivity occurs when the electrons transferred from the oxygen-vacant substrate suppress the otherwise pronounced SDWs in single-layer FeSe. Beyond providing a comprehensive understanding of FeSe films and directions to further enhance its T(c), we map out the phase diagram of FeSe as a function of lattice constant, which contains all the essential physics of Fe-HTS. With the simplest structure, cleanest composition and single tuning parameter, monolayer FeSe is an ideal system for testing theories of Fe-HTS.
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: Shiyong
authors.initials: S
authors.lastname: Tan
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Miao
authors.initials: M
authors.lastname: Xia
authors.forename: Zirong
authors.initials: Z
authors.lastname: Ye
authors.forename: Fei
authors.initials: F
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Xie
authors.forename: Rui
authors.initials: R
authors.lastname: Peng
authors.forename: Difei
authors.initials: D
authors.lastname: Xu
authors.forename: Qin
authors.initials: Q
authors.lastname: Fan
authors.forename: Haichao
authors.initials: H
authors.lastname: Xu
authors.forename: Juan
authors.initials: J
authors.lastname: Jiang
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.forename: Xinchun
authors.initials: X
authors.lastname: Lai
authors.forename: Tao
authors.initials: T
authors.lastname: Xiang
authors.forename: Jiangping
authors.initials: J
authors.lastname: Hu
authors.forename: Binping
authors.initials: B
authors.lastname: Xie
authors.forename: Donglai
authors.initials: D
authors.lastname: Feng