Prediction of the in-Gap States Above the Top of the Valence Band in the Undoped Insulating Cuprates due to Spin-Polaron Effect

TL;DR

This paper uses a generalized tight binding approach to calculate the quasiparticle band structure of undoped cuprates, revealing spin-fluctuation-induced in-gap states above the valence band top, which relate to experimental ARPES observations.

Contribution

It introduces a theoretical calculation of in-gap states in undoped cuprates caused by spin fluctuations, linking them to experimental ARPES features.

Findings

In-gap states appear above the valence band top due to spin fluctuations.

These states can be observed as weak satellites in ARPES experiments.

The model explains the origin of in-gap states in undoped cuprates.

Abstract

In the framework of the generalized tight binding method we have calculated the quasiparticle band structure and the spectral functions of the undoped cuprates like $La_2 CuO_4$, $Sr_2CuO_2Cl_2$ etc. Due to spin fluctuations the in-gap state appears above the top of the valence band in the undoped antiferromagnetic insulator similar to in-gap states induced by hole doping. In the ARPES experiments the in-gap states can be detected as weak low energy satellites.