Fermi blockade of the electron-phonon interaction: why strong coupling effects may not be seen in optimally doped high temperature superconductors

TL;DR

This paper investigates how strong electron-phonon interactions are masked by Fermi blockade effects in doped high-temperature superconductors, explaining why strong coupling signatures are not observed at optimal doping levels.

Contribution

It demonstrates through Monte Carlo simulations that Fermi blockade suppresses strong EPI signatures at higher carrier densities, aligning with experimental findings.

Findings

Strong EPI is evident at low carrier concentration.

Fermi blockade effects mask EPI at higher densities.

Results align with experimental observations in doped superconductors.

Abstract

We study how manifestations of strong electron-phonon interaction (EPI) depend on the carrier concentration by solving the two-dimensional Holstein model for the spin-polarized fermions using an approximation free bold-line diagrammatic Monte Carlo (BDMC) method. We show that the strong EPI, obviously present at very small Fermion concentration, is masked by the Fermi blockade effects and Migdal's theorem to the extent that it manifests itself as moderate one at large carriers densities. Suppression of strong EPI fingerprints is in agreement with experimental observations in doped high temperature superconductors