Oxygen Vacancy Induced Flat Phonon Mode at FeSe /SrTiO3 interface

Abstract

A high-frequency optical phonon mode of SrTiO3 (STO) was found to assist the high-temperature superconductivity observed recently at the interface between monolayer FeSe and STO substrate. However, the origin of this mode is not clear. Through first-principles calculations, we find that there is a novel polar phonon mode on the surface layers of the STO substrate, which does not exist in the STO crystals. The oxygen vacancies near the FeSe/STO interface drives the dispersion of this phonon mode to be flat and lowers its energy, whereas the charge transfer between STO substrate and FeSe monolayer further reduces its energy to 81 meV. This energy is in good agreement with the experimental value fitted by Lee et al. for the phonon mode responsible for the observed replica band separations and the increased superconducting gap. The oxygen-vacancy-induced flat and polar phonon mode provides clues for understanding the origin of high Tc superconductivity at the FeSe/STO interface.

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References in corpus (19)

• Phonons and related properties of extended systems from density-functional perturbation theory
• 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
• Unveiling a two-dimensional electron gas with universal subbands at the surface of SrTiO3
• 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
• Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO
• Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor
• Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surface
• Direct observation of high temperature superconductivity in one-unit-cell FeSe films
• Critical role of substrate in the high temperature superconductivity of single layer FeSe on Nb:BaTiO${}_3$
• Enhanced superconductivity and evidence for novel pairing in single-layer FeSe on SrTiO3 thin film under large tensile strain
• High temperature superconducting FeSe films on SrTiO3 substrates
• Origin of the large phonon band-gap in SrTiO3 and the vibrational signatures of ferroelectricity in ATiO3 perovskite: First principles lattice dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3
• Electronic Evidence of an Insulator-Superconductor Transition in Single-Layer FeSe/SrTiO3 Films
• Dichotomy of Electronic Structure and Superconductivity between Single-Layer and Double-Layer FeSe/SrTiO3 Films
• The interfacial effects on the spin density wave in FeSe/SrTiO3 thin film
• Observation of a two-dimensional electron gas at the surface of annealed SrTiO3 single crystals by scanning tunneling spectroscopy

Cited by in corpus (22)

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• Atomically Resolved FeSe/SrTiO3(001) Interface Structure by Scanning Transmission Electron Microscopy
• Interface high-temperature superconductivity
• Superconductivity dichotomy in K-coated single and double unit cell FeSe films on SrTiO3
• 20 K superconductivity in heavily electron doped surface layer of FeSe bulk crystal
• Ab initio Study of Cross-Interface Electron-Phonon Couplings in FeSe Thin Films on SrTiO${}_3$ and BaTiO${}_3$
• Multiband full-bandwidth anisotropic Eliashberg theory of interfacial electron-phonon coupling and high-T${}_c$ superconductivity in FeSe/SrTiO${}_3$
• Atomic-scale observation of localized phonons at FeSe/SrTiO3 interface
• Magnetic fluctuations and spin-spirals in single-layer FeSe
• Unconventional pairing in single FeSe layers
• Self-consistent temperature dependence of quasiparticle bands in monolayer FeSe on SrTiO${}_3$
• Band structure and charge doping effects of potassium-adsorbed FeSe/SrTiO3 system
• Multichannel superconductivity of monolayer FeSe on SrTiO${}_3$: Interplay of spin fluctuations and electron-phonon interaction
• Soft phonons in the interface layer of the STO substrate can explain high temperature superconductivity in one unit cell FeSe
• Effects of interface oxygen vacancies on electronic bands of FeSe/SrTiO3(001)
• Towards exact solutions for the superconducting $T_c$ induced by electron-phonon interaction
• First-principles study of FeSe epitaxial films on SrTiO3
• Observation of two distinct superconducting domes under pressure in tetragonal FeS
• Duality and degeneracy lifting in two-dimensional electron liquids on SrTiO${}_3$(001)
• Theoretical study of phonon-mediated superconductivity beyond Migdal-Eliashberg approximation and Coulomb pseudopotential