title: Tuning the band structure and superconductivity in single-layer FeSe by interface engineering.
abstract: The interface between transition metal compounds provides a rich playground for emergent phenomena. Recently, significantly enhanced superconductivity has been reported for single-layer FeSe on Nb-doped SrTiO3 substrate. Yet it remains mysterious how the interface affects the superconductivity. Here we use in situ angle-resolved photoemission spectroscopy to investigate various FeSe-based heterostructures grown by molecular beam epitaxy, and uncover that electronic correlations and superconducting gap-closing temperature (Tg) are tuned by interfacial effects. Tg up to 75 K is observed in extremely tensile-strained single-layer FeSe on Nb-doped BaTiO3, which sets a record high pairing temperature for both Fe-based superconductor and monolayer-thick films, providing a promising prospect on realizing more cost-effective superconducting device. Moreover, our results exclude the direct correlation between superconductivity and tensile strain or the energy of an interfacial phonon mode, and highlight the critical and non-trivial role of FeSe/oxide interface on the high Tg, which provides new clues for understanding its origin.
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: R
authors.initials: R
authors.lastname: Peng
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: H C
authors.initials: HC
authors.lastname: Xu
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: S Y
authors.initials: SY
authors.lastname: Tan
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, China.
authors.forename: H Y
authors.initials: HY
authors.lastname: Cao
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: M
authors.initials: M
authors.lastname: Xia
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: X P
authors.initials: XP
authors.lastname: Shen
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: Z C
authors.initials: ZC
authors.lastname: Huang
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: C H P
authors.initials: CH
authors.lastname: Wen
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Song
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: T
authors.initials: T
authors.lastname: Zhang
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: B P
authors.initials: BP
authors.lastname: Xie
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, China.
authors.forename: X G
authors.initials: XG
authors.lastname: Gong
authors.affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China [2] Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: D L
authors.initials: DL
authors.lastname: Feng