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 (10)

• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity
• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Quantum Hall effect in a bulk antiferromagnet EuMnBi${}_2$ with magnetically confined two-dimensional Dirac fermions
• 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
• Atomic and electronic structures of FeSe monolayer and bilayer thin films on SrTiO${}_3$ (001): a first-principles study
• Interface high-temperature superconductivity
• Oxygen Vacancy Induced Flat Phonon Mode at FeSe /SrTiO3 interface
• 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${}^{2+}$

Cited by in corpus (5)

• Tuning the electronic structure of α-antimonene monolayer through interface engineering
• Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates
• Stoichiometry and defect superstructures in epitaxial FeSe films on SrTiO3
• Electronic structure and signature of Tomonaga-Luttinger liquid state in epitaxial CoSb${}_{1-x}$ nanoribbons
• Role of electric fields on enhanced electron correlation in surface-doped FeSe