Influence of the Diagonal and Off-Diagonal Electron–Phonon Interactions on the Formation of Local Polarons and Their Band Structure in Materials with Strong Electron Correlations

• Published in: Journal of experimental and theoretical physics 2018-05, Vol.126 (5), p.683-698
• Main Authors: Shneyder, E. I., Makarov, I. A., Zotova, M. V., Ovchinnikov, S. G.
• Format: Article
• Language: English
• Subjects: Analysis; Antiferromagnetism; Band structure; Band structure of solids; Classical and Quantum Gravitation; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Copper compounds; CUPRATES; ELECTRON CORRELATION; Electronic Properties of Solid; Electrons; Elementary Particles; INTERACTIONS; LINE WIDTHS; MATHEMATICAL EVOLUTION; Particle and Nuclear Physics; Photoelectric emission; PHOTOELECTRON SPECTROSCOPY; Physics; Physics and Astronomy; POLARONS; Quantum Field Theory; Relativity Theory; Solid State Physics; SPECTRAL FUNCTIONS; TEMPERATURE DEPENDENCE; Valence band
• ISSN: 1063-7761; 1090-6509
• DOI: 10.1134/S1063776118050059

For systems with strong electron correlations and strong electron–phonon interaction, we analyze the electron–phonon interaction in local variables. The effects of the mutual influence of electron–electron and electron–phonon interactions that determine the structure of local Hubbard polarons are described. Using a system containing copper–oxygen layers as an example, we consider the competition between the diagonal and off-diagonal interactions of electrons with the breathing mode as the polaron band structure is formed within a corrected formulation of the polaron version of the generalized tight-binding method. The band structure of Hubbard polarons is shown to depend strongly on the temperature due to the excitation of Franck–Condon resonances. For an undoped La 2 CuO 4 compound we have described the evolution of the band structure and the spectral function from the hole dispersion in an antiferromagnetic insulator at low temperatures with the valence band maximum at point (π/2, π/2) to the spectrum with the maximum at point (π, π) typical for the paramagnetic phase. The polaron line width at the valence band top and its temperature dependence agree qualitatively with angle-resolved photoemission spectroscopy for undoped cuprates.