The phonon mechanism explanation of the superconductivity dichotomy between FeSe and FeS monolayers on STO and other substrates

Abstract

It was observed recently (K. Shigekawa et al, PNAS 116, 2470 (2019)) that while monolayer iron chalcigenide FeSe on SrTiO3 (STO) substrate has a very high critical temperature, its chemical and structural "twin" material FeS=STO has a very low Tc if any. To explain this the substrate interfacial phonon model of superconductivity in iron chalcogenides is further developed. The main glue is the oxygen ion (60mev) vibrations longitudinal optical (LO) mode. The mode propagates mainly in the TiO2 layer adjacent to the monolayer (and genrally present also in similar highly polarized ionic crystals like BaTiO3; rutile, anatase). It has stronger electron - phonon coupling to electron gas in FeSe than a well known (100mev) harder LO mode. It is shown that while (taking into account screened Coulomb repulsion efects) the critical temperature of FeSe on STO and TiO2 is above 65K, it becomes less than 5K for FeS due to two factors suppressing the electron - phonon coupling. The efective mass in the later is twice smaller and in addition the distance between the electron gas in FeSe to the vibrating substrate oxygen atoms is 15% smaller than in FeS reducinng the central peak in electron-phonon interaction. The theory is extended to other ionic insulating substrates.

References in corpus (44)

• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films
• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor
• Enhancement of superconducting transition temperature of FeSe by intercalation of a molecular spacer layer
• Structure determination and coexistence of superconductivity and antiferromagnetic order in (Li0.8Fe0.2)OHFeSe
• Superconductivity at 32 K in single crystal Rb${}_{0.78}$Fe${}_2$Se${}_{1.78}$}
• Transition of stoichiometricSr2VO3FeAs to a superconducting state at 37.2 K
• Evolution of high-temperature superconductivity from low-Tc phase tuned by carrier concentration in FeSe thin flakes
• Phonon-enhanced superconductivity at the FeSe/SrTiO3 interface
• Critical role of substrate in the high temperature superconductivity of single layer FeSe on Nb:BaTiO${}_3$
• Common Electronic Origin of Superconductivity in (Li,Fe)OHFeSe Bulk Superconductor and Single-Layer FeSe/SrTiO3 Films
• Plain s-wave superconductivity in single-layer FeSe on SrTiO3 probed by scanning tunneling microscopy
• Enhanced superconductivity and evidence for novel pairing in single-layer FeSe on SrTiO3 thin film under large tensile strain
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Enhanced superconductivity due to forward scattering in FeSe thin films on SrTiO3 substrates
• Universal Substrate Effect on the Superconductivity of FeSe Monolayer Films
• High-temperature superconductivity in single-unit-cell FeSe films on anatase TiO2(001)
• The Role of SrTiO3 Phonon Penetrating into thin FeSe Films in the Enhancement of Superconductivity
• Interface enhanced electron-phonon coupling and high temperature superconductivity in potassium-coated ultra-thin FeSe films on SrTiO3
• New iron-based arsenide oxides (Fe2As2)(Sr4M2O6)(M = Sc, Cr)
• Topological Phases in the Single-Layer FeSe
• Interface high-temperature superconductivity
• Atomically Resolved FeSe/SrTiO3(001) Interface Structure by Scanning Transmission Electron Microscopy
• High Tc via spin fluctuations from incipient bands: application to monolayers and intercalates of FeSe
• Electron phonon coupling versus photoelectron energy loss at the origin of replica bands in photoemission of FeSe on SrTiO${}_3$
• Thickness dependence of superconductivity and superconductor-insulator transition in ultrathin FeSe films on SrTiO3(001) substrate
• Evolution of spin excitations from bulk to monolayer FeSe
• Pairing in the Two-Dimensional Hubbard Model from Weak to Strong Coupling
• 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${}_3$
• Orbital selectivity in electron correlations and superconducting pairing of iron-based superconductors
• Aspects of electron-phonon interactions with strong forward scattering in FeSe Thin Films on SrTiO${}_3$ substrates
• On peculiarities of superconductivity in the single-layer FeSe/SrTiO3 interfa
• Dichotomy of superconductivity between monolayer FeS and FeSe
• Lattice Dynamics of Ultrathin FeSe Films on SrTiO3
• The electron-phonon interaction with forward scattering peak is a relevant approach to high Tc superconductivity in FeSe films on SrTiO3 and TiO2
• Eliashberg theory for spin-fluctuations mediated superconductivity -- Application to bulk and monolayer FeSe
• Phonon Boost Effect on the $S^{\pm }$-wave Superconductor with Incipient Band
• 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
• Superconductivity in 2D electron gas induced by high energy optical phonon mode and large polarization of the STO substrate
• Enhanced superconductivity in FeSe/SrTiO${}_3$ from the combination of forward scattering phonons and spin fluctuations
• Origin of the Electronic Structure in Single-Layer FeSe/SrTiO3 Films