Electron–phonon coupling in heavily electron-doped bulk FeSe: a first-principles investigation

Abstract

We present the results of electron–phonon coupling (EPC) in heavily electron-doped FeSe, based on the first-principles calculation and Wannier interpolation. It is found that the EPC constant λ can be improved by 31% at a doping level of 0.4 e/cell, with respect to the pristine case. The change of Fermi surface nesting function around M point dominates the enhancement of λ. Nevertheless, the superconducting Tc of FeSe is only 0.01 mK at 0.4 e/cell doping, determined through McMillian–Allen–Dynes formula. Our findings clarify that electron doping alone can not raise the Tc to the experimental value within phonon-mediated picture.