Unconventional pairing in single FeSe layers

Abstract

The pairing mechanism in iron-based superconductors is believed to be unconventional, i.e. not phonon-mediated. The achieved transition temperatures Tc in these superconductors are still significantly below those of some of the cuprates, with the exception of single layer FeSe films on SrTiO3 showing a Tc between 60 and 100 K, i.e. an order of magnitude larger than in bulk FeSe. This enormous increase of Tc demonstrates the potential of interface engineering for superconductivity, yet the underlying mechanism of Cooper pairing is not understood. Both conventional and unconventional mechanisms have been discussed. Here we report a direct measurement of the electron-boson coupling function in FeSe on SrTiO3 using inelastic electron scattering which shows that the excitation spectrum becomes fully gapped below Tc strongly supporting a predominantly electronic pairing mechanism. We also find evidence for strong electron-phonon coupling of low energy electrons, which is however limited to regions near structural domain boundaries.

10 pages, 7 figures

References in corpus (13)

• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Theory of magnetic excitations in iron-based layered superconductors
• Phonon-enhanced superconductivity at the FeSe/SrTiO3 interface
• Monolayer FeSe on SrTiO${}_3$
• Electronic Structure and Superconductivity of FeSe-Related Superconductors
• Universal Substrate Effect on the Superconductivity of FeSe Monolayer Films
• Ubiquitous strong electron phonon coupling at the interface of FeSe/SrTiO3
• High-temperature superconductivity in one-unit-cell FeSe films
• Electron phonon coupling versus photoelectron energy loss at the origin of replica bands in photoemission of FeSe on SrTiO${}_3$
• Oxygen Vacancy Induced Flat Phonon Mode at FeSe /SrTiO3 interface
• A compact ultrahigh vacuum scanning tunneling microscope with dilution refrigeration
• Lattice Dynamics of Ultrathin FeSe Films on SrTiO3

Cited by in corpus (14)

• Electronic structure of quantum materials studied by angle-resolved photoemission spectroscopy
• Eliashberg theory for spin-fluctuations mediated superconductivity -- Application to bulk and monolayer FeSe
• Heterostructural one-unit-cell FeSe/SrTiO3: from high-temperature superconductivity to topological states
• High-Temperature Majorana Fermions in Magnet-Superconductor Hybrid Systems
• Electronic and phononic properties of a two dimensional electron gas coupled to dipolar phonons via small-momentum-transfer scattering
• Multichannel superconductivity of monolayer FeSe on SrTiO${}_3$: Interplay of spin fluctuations and electron-phonon interaction
• Direct probing of a large spin-orbit coupling in the FeSe superconducting monolayer on STO: Evidence for nontrivial topological states
• Phase competition in a one-dimensional three-orbital Hubbard-Holstein model
• Direct evidence of a charge depletion region at the interface of Van der Waals monolayers and dielectric oxides: The case of superconducting FeSe/STO
• Effect of the additional Se layer on the electronic structure of iron-based superconductor FeSe/SrTiO${}_3$
• Bosonic excitation spectra of superconducting $\mathrm{B}{\mathrm{i}}_2\mathrm{S}{\mathrm{r}}_2\mathrm{CaC}{\mathrm{u}}_2{\mathrm{O}}_{8+\delta }$ and $\mathrm{YB}{\mathrm{a}}_2\mathrm{C}{\mathrm{u}}_3{\mathrm{O}}_{6+\mathrm{x}}$ extracted from scanning tunneling spectra
• Cavity quantum-electrodynamical polaritonically enhanced electron-phonon coupling and its influence on superconductivity
• Band structure of organic-ion-intercalated (EMIM)${}_x$FeSe superconductor
• Temperature evolution of the Fermi surface of the FeSe monolayer on SrTiO${}_3$