Origin of charge transfer and enhanced electron-phonon coupling in single unit-cell FeSe films on SrTiO3

Abstract

Interface charge transfer and electron-phonon coupling have been suggested to play a crucial role in the recently discovered high-temperature superconductivity of single unit-cell FeSe films on SrTiO3. However, their origin remains elusive. Here, using ultraviolet photoemission spectroscopy (UPS) and element-sensitive X-ray photoemission spectroscopy (XPS), we identify the strengthened Ti-O bond that contributes to the interface enhanced electron-phonon coupling and unveil the band bending at the FeSe/SrTiO3 interface that leads to the charge transfer from SrTiO3 to FeSe films. We also observe band renormalization that accompanies the onset of superconductivity. Our results not only provide valuable insights into the mechanism of the interface-enhanced superconductivity, but also point out a promising route towards designing novel superconductors in heterostructures with band-bending induced charge transfer and interfacial enhanced electron-phonon coupling.

References in corpus (32)

• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films
• Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity
• Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3
• Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films
• Observation of Majorana fermions with spin selective Andreev reflection in the vortex of topological superconductor
• Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor
• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Direct observation of high temperature superconductivity in one-unit-cell FeSe films
• Evolution of high-temperature superconductivity from low-Tc phase tuned by carrier concentration in FeSe thin flakes
• Electric-field-induced superconductivity in electrochemically-etched ultrathin FeSe films on SrTiO3 and MgO
• Quantum Hall effect in a bulk antiferromagnet EuMnBi${}_2$ with magnetically confined two-dimensional Dirac fermions
• Observation of universal strong orbital-dependent correlation effects in iron chalcogenides
• Anomalous correlation effects and unique phase diagram of electron doped FeSe revealed by angle resolved photoemission spectroscopy
• Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films
• Universal Substrate Effect on the Superconductivity of FeSe Monolayer Films
• Evidence for Strong Itinerant Spin Fluctuations in the Normal State of CeFeAsO(0.89)F(0.11) Iron-Oxypnictides
• High-temperature superconductivity in single-unit-cell FeSe films on anatase TiO2(001)
• Onset of the Meissner effect at 65 K in FeSe thin film grown on Nb doped SrTiO3 substrate
• The Role of SrTiO3 Phonon Penetrating into thin FeSe Films in the Enhancement of Superconductivity
• Atomic and electronic structures of FeSe monolayer and bilayer thin films on SrTiO${}_3$ (001): a first-principles study
• Interface enhanced electron-phonon coupling and high temperature superconductivity in potassium-coated ultra-thin FeSe films on SrTiO3
• Interface high-temperature superconductivity
• Atomically Resolved FeSe/SrTiO3(001) Interface Structure by Scanning Transmission Electron Microscopy
• Co-substitution effects on the Fe-valence in the BaFe2As2 superconducting compound: A study of hard x-ray absorption spectroscopy
• Superconductivity dichotomy in K-coated single and double unit cell FeSe films on SrTiO3
• Oxygen Vacancy Induced Flat Phonon Mode at FeSe /SrTiO3 interface
• Electron correlation in FeSe superconductor studied by bulk-sensitive photoemission spectroscopy
• The role of double TiO2 layers at the interface of FeSe/SrTiO3 superconductors
• Do Se vacancies electron dope monolayer FeSe?
• Electronic structure of single-crystalline Sr(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ probed by x-ray absorption spectroscopy: Evidence for isovalent substitution of Fe${}^{2+}$ by Co${}^{2+}$

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• Observation of topological transition in high-T${}_c$ superconductor FeTe${}_{1-x}$Se${}_x$/SrTiO${}_3$(001) monolayers
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• Heterostructural one-unit-cell FeSe/SrTiO3: from high-temperature superconductivity to topological states
• Tuning stoichiometry and its impact on superconductivity of monolayer and multilayer FeSe on SrTiO3
• Engineering ultra-strong electron-phonon coupling and nonclassical electron transport in crystalline gold with nanoscale interfaces
• Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates
• Electronic structure and signature of Tomonaga-Luttinger liquid state in epitaxial CoSb${}_{1-x}$ nanoribbons
• Stoichiometry and defect superstructures in epitaxial FeSe films on SrTiO3
• Helical metals and insulators and sheet singularity of inflated Berry monopole
• Role of electric fields on enhanced electron correlation in surface-doped FeSe
• Superconductivity of the FeSe/SrTiO3 Interface in the View of BCS-BEC Crossover
• Evidence of electron interaction with an unidentified bosonic mode in superconductor CsCa${}_2$Fe${}_4$As${}_4$F${}_2$
• Interface suppressed nematicity and enhanced superconductivity of FeSe/NdFeO3 in the low doping regime
• Imaging Se diffusion across the FeSe/SrTiO${}_3$ interface
• Modulation doping of the FeSe monolayer on SrTiO${}_3$
• Direct evidence of a charge depletion region at the interface of Van der Waals monolayers and dielectric oxides: The case of superconducting FeSe/STO
• Lateral quantum confinement effect on monolayer high-Tc superconductors
• Capping layer influence and isotropic in-plane upper critical field of the superconductivity at the FeSe/SrTiO3 interface
• Study on fluctuations of interface-enhanced superconductivity in ultrathin FeSe/SrTiO3 by the Nernst effect
• Studies of superconductivity of Fe chalcogenides in films grown by PLD technique
• Inferior interfacial superconductivity in 1 UC FeSe/SrVO${}_3$/SrTiO${}_3$ with screened interfacial electron-phonon coupling
• Enhanced superconductivity in PbTe-In hybrids
• Fabrication of oxide/FeSe multilayer films using the PLD technique
• Temperature evolution of the Fermi surface of the FeSe monolayer on SrTiO${}_3$