Large electron-phonon interactions from FeSe phonons in a monolayer

摘要

We show that electron-phonon coupling can induce strong electron pairing inan FeSe monolayer on a SrTiO3 substrate (experimental indications forsuperconducting Tc are between 65 and 109K). The role of the SrTiO3 substratein increasing the coupling is two-fold. First, the interaction of the FeSe andTiO2 terminated face of SrTiO3 prevents the FeSe monolayer from undergoing ashear-type (orthorhombic, nematic) structural phase transition. Second, thesubstrate allows an anti-ferromagnetic ground state of FeSe which openselectron-phonon coupling channels within the monolayer that are prevented bysymmetry in the non-magnetic phase. The spectral function for theelectron-phonon coupling (alpha2F) in our calculations agrees well withinelastic tunneling data.