Electron-phonon coupling in the self-consistent Born approximation of the tJ model

O. Gunnarsson and O. Rösch
Phys. Rev. B 73, 174521 – Published 23 May 2006

Abstract

We study an undoped tJ model with electron-phonon interaction using the self-consistent Born approximation (SCBA). By neglecting vertex corrections, the SCBA solves a boson-holon model, where a holon couples to phonons and magnons. Comparison with exact diagonalization results for the tJ model suggests that the SCBA describes the electron-phonon interaction fairly accurately over a substantial range of Jt values. Exact diagonalization of the boson-holon model shows that the deviations are mainly due to the neglect of vertex corrections for small Jt and due to the replacement of the tJ model by the boson-holon model for large Jt. For typical values of Jt, the electron-phonon part Σep of the electron self-energy has comparable contributions from the second-order diagram in the electron-phonon interaction and a phonon-induced change of magnon diagrams. A very simple approximation to Σep gives a rather accurate effective mass. Using this approximation, we study the factors influencing the electron-phonon interaction. Typically, we find that the magnons nominally have a stronger coupling to the holon than the phonons. The phonons, nevertheless, drive the formation of small polarons (self-localization) due to important differences between the character of the phonon and magnon couplings.

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  • Received 14 February 2006

DOI:https://doi.org/10.1103/PhysRevB.73.174521

©2006 American Physical Society

Authors & Affiliations

O. Gunnarsson and O. Rösch

  • Max-Planck-Institut für Festkörperforschung, D-70506 Stuttgart, Germany

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Issue

Vol. 73, Iss. 17 — 1 May 2006

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