Spin fluctuations influence on quasiparticle spectrum of realistic p-d model

TL;DR

This paper investigates how spin fluctuations affect the quasiparticle spectrum in a realistic p-d model for CuO2 layers, showing that including these fluctuations improves agreement with ARPES experimental data.

Contribution

It demonstrates that spin fluctuations beyond the Hubbard-I approximation significantly influence the quasiparticle spectrum in the p-d model.

Findings

Triplet states contribute to the valence band top.

Including spin fluctuations improves spectral agreement with experiments.

Quasiparticle spectrum aligns well with ARPES data for Bi2212.

Abstract

In the present work the multiband p-d model for $CuO_2$-layer is treated. It was shown that for the realistic set of parameters besides Zhang-Rice two-particle singlet there is non-negligible contribution of two-particle triplet state to the top of the valence band. Also shown, that to gain quantitative agreement with experimental data the minimal approximation should include the spin fluctuations beyond the Hubbard-I scheme. Quasiparticle spectrum, obtained in this approximation, is in fairly good agreement with ARPES data on Bi2212 High-$T_c$ compound.