Temperature dependence of the polaronic band structure in strongly correlated electron systems with strong electron-phonon interaction

TL;DR

This study models how temperature influences the electronic structure of strongly correlated electron systems with significant electron-phonon interactions, revealing spectral and band structure changes consistent with experimental observations in cuprates.

Contribution

It introduces a polaronic version of the generalized tight binding method to analyze temperature effects on the electronic structure of cuprates within a three-band p-d-Holstein model.

Findings

Spectral peaks broaden and shift with increasing temperature.

Bandwidth increases and the energy gap decreases as temperature rises.

Results qualitatively match ARPES spectra temperature dependence in undoped cuprates.

Abstract

In this work we investigate temperature dependence of electronic structure of system with strong electronic correlations and strong electron-phonon interaction modeling cuprates in the frameworks of the three-band p-d-Holstein model by a polaronic version of the generalized tight binding (GTB) method. Within this approach the electronic structure is formed by polaronic quasiparticles constructed as excitations between initial and final polaronic multielectron states. Temperature effect is taken into account by occupation numbers of local excited polaronic states and variations in the magnitude of spin-spin correlation functions and it is manifested in the redistribution of the spectral weight over the Hubbard polaron subbands, and the temperature dependent band structure. Temperature increasing leads to broadening of the spectral function peak at the top of the valence band, shift of the peak, the decreasing of the peak intensity, the growth of bandwidth and reduction of the insulator energy gap. These effects are in a qualitative agreement to the temperature dependence of the ARPES spectra observed in the undoped HTSC cuprates.