Fermi blockade of the strong electron\u2013phonon interaction in modelled optimally doped high temperature superconductors

Andrey S Mishchenko,Igor S Tupitsyn,Naoto Nagaosa,Nikolay Prokof’Ev

doi:10.1038/s41598-021-89059-w

Abstract

We study how manifestations of strong electron–phonon interaction 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 method. We show that the strong electron–phonon interaction, 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 electron–phonon interaction fingerprints is in agreement with experimental observations in doped high temperature superconductors.

Highlights

We study how manifestations of strong electron–phonon interaction 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 method
Signatures of strong electron–phonon interaction (EPI) are observed only at δ < 0.1 that roughly corresponds to γ ≈ 1, which can be interpreted as the “Fermi blockade” of EPI manifestations at large concentration by the Pauli exclusion principle
We obtained approximation-free results for the concentration dependence of the quasiparticle residue Z and kink caused by the strong electron–phonon interaction in the spin-polarized two-dimensional Holstein model on the square lattice

Summary

Introduction

We study how manifestations of strong electron–phonon interaction 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 method. The crossover between the two regimes is expected to take place at ω ph ∼ εF , where ω ph is the phonon frequency and εF is the Fermi energy, and it can be addressed by the approximation free diagrammatic Monte Carlo methods[8,27,28,29] To this end, we consider a spin polarized (SP) two-dimensional (2D) lattice system in order to avoid system instabilities that would be triggered by the strong EPI in continuous and spin-balanced systems, such as structural transitions or a singlet on-site bipolaron formation at ≈ 0.5 (in 2D)[30] with the concomitant superconducting state.

Objectives

Methods

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Discussion

Conclusion