title: Anomalous correlation effects and unique phase diagram of electron-doped FeSe revealed by photoemission spectroscopy.
abstract: FeSe layer-based superconductors exhibit exotic and distinctive properties. The undoped FeSe shows nematicity and superconductivity, while the heavily electron-doped KxFe2-ySe2 and single-layer FeSe/SrTiO3 possess high superconducting transition temperatures that pose theoretical challenges. However, a comprehensive study on the doping dependence of an FeSe layer-based superconductor is still lacking due to the lack of a clean means of doping control. Through angle-resolved photoemission spectroscopy studies on K-dosed thick FeSe films and FeSe0.93S0.07 bulk crystals, here we reveal the internal connections between these two types of FeSe-based superconductors, and obtain superconductivity below ∼ 46 K in an FeSe layer under electron doping without interfacial effects. Moreover, we discover an exotic phase diagram of FeSe with electron doping, including a nematic phase, a superconducting dome, a correlation-driven insulating phase and a metallic phase. Such an anomalous phase diagram unveils the remarkable complexity, and highlights the importance of correlations in FeSe layer-based superconductors.
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: C H P
authors.initials: CH
authors.lastname: Wen
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: H C
authors.initials: HC
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: C
authors.initials: C
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: Z C
authors.initials: ZC
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: X
authors.initials: X
authors.lastname: Lou
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Pu
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Song
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: B P
authors.initials: BP
authors.lastname: Xie
authors.affiliation: Institute of Physics, Goethe University Frankfurt, 60438 Frankfurt, Germany.|Center for High Pressure Science and Technology Advanced Research, 1690 Cailun Road, Shanghai 201203, China.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Abdel-Hafiez
authors.affiliation: Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, 119991 Moscow , Russia.
authors.forename: D A
authors.initials: DA
authors.lastname: Chareev
authors.affiliation: Low Temperature Physics and Superconductivity Department, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: A N
authors.initials: AN
authors.lastname: Vasiliev
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: R
authors.initials: R
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: D L
authors.initials: DL
authors.lastname: Feng