Aspects of electron-phonon interactions with strong forward scattering in FeSe Thin Films on SrTiO${}_3$ substrates

Abstract

Mono- and multilayer FeSe thin films grown on SrTiO${}_3$ and BiTiO${}_3$ substrates exhibit a greatly enhanced superconductivity over that found in bulk FeSe. A number of proposals have been advanced for the mechanism of this enhancement. One possibility is the introduction of a cross-interface electron-phonon ($e$-$ph$) interaction between the FeSe electrons and oxygen phonons in the substrates that is peaked in the forward scattering (small $\mathbf{q}$) direction due to the two-dimensional nature of the interface system. Motivated by this, we explore the consequences of such an interaction on the superconducting state and electronic structure of a two-dimensional system using Migdal-Eliashberg theory. This interaction produces not only deviations from the expectations of conventional phonon-mediated pairing but also replica structures in the spectral function and density of states, as probed by angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and quasi-particle interference imaging. We also discuss the applicability of Migdal-Eliashberg theory for a situation where the \ep interaction is peaked at small momentum transfer and in the FeSe/STO system.

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Cited by in corpus (28)

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• Superconductivity in FeSe thin films driven by the interplay between nematic fluctuations and spin-orbit coupling
• Electron phonon coupling versus photoelectron energy loss at the origin of replica bands in photoemission of FeSe on SrTiO${}_3$
• Langevin Simulations of a Long Range Electron Phonon Model
• Full-bandwidth Eliashberg theory of superconductivity beyond Migdal's approximation
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• Interfacial Electron-Phonon Coupling Constants Extracted from Intrinsic Replica Bands in Monolayer FeSe/SrTiO${}_3$
• Unconventional pairing in single FeSe layers
• Electronic structure of FeSe monolayer superconductors: shallow bands and correlations
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• Phonon Boost Effect on the $S^{\pm }$-wave Superconductor with Incipient Band
• On the origin of the shallow and "replica" bands in FeSe monolayer superconductors
• Multichannel superconductivity of monolayer FeSe on SrTiO${}_3$: Interplay of spin fluctuations and electron-phonon interaction
• Superconductivity in 2D electron gas induced by high energy optical phonon mode and large polarization of the STO substrate
• Soft phonons in the interface layer of the STO substrate can explain high temperature superconductivity in one unit cell FeSe
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• Electron - phonon coupling in Eliashberg - McMillan theory beyond adiabatic approximation
• Constraints on the total coupling strength to bosons in iron based superconductors
• Manifestations of the electron-phonon interaction range in angle resolved photoemission spectra
• Intrinsic charge dynamics in high-Tc AFeAs(O,F) superconductors
• Optimal Boson energy for superconductivity in the Holstein model
• The phonon mechanism explanation of the superconductivity dichotomy between FeSe and FeS monolayers on STO and other substrates
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• Non-thermal pairing glue of electrons in the steady state