Electron dynamics in the normal state of cuprates: spectral function, Fermi surface and ARPES data

TL;DR

This paper investigates how electron-phonon interactions influence the spectral properties and Fermi surface of cuprates in the normal state, using the t-J model and Hubbard-I approximation to explain ARPES data and spectral features.

Contribution

It presents an exact solution for polaron bands considering strong correlations and local electron-phonon binding within the t-J model, explaining spectral features observed in ARPES.

Findings

Correlation gap may form at the Fermi level depending on doping and hopping parameters.

Electron-phonon binding enhances coherence of electron-polaron excitations near the Fermi level.

The kink in ARPES spectra is explained by the polaron band structure near the mode frequency.

Abstract

An influence of the electron-phonon interaction on excitation spectrum and damping in a narrow band electron subsystem of cuprates has been investigated. Within the framework of the t-J model an approach to solving a problem of account of both strong electron correlations and local electron-phonon binding with characteristic Einstein mode $\omega _0$ in the normal state has been presented. In approximation Hubbard-I it was found an exact solution to the polaron bands. We established that in the low-dimensional system with a pure kinematic part of Hamiltonian a complicated excitation spectrum is realized. It is determined mainly by peculiarities of the lattice Green's function. In the definite area of the electron concentration and hopping integrals a correlation gap may be possible on the Fermi level. Also, in specific cases it is observed a doping evolution of the Fermi surface. We found that the strong electron-phonon binding enforces a degree of coherence of electron-polaron excitations near the Fermi level and spectrum along the nodal direction depends on wave vector module weakly. It corresponds to ARPES data. A possible origin of the experimentally observed kink in the nodal direction of cuprates is explained by fine structure of the polaron band to be formed near the mode -$\omega _0$.