Dominance of many-body effects over one-electron mechanism for band structure doping dependence in Nd$_{2-x}$Ce$_x$CuO$_4$: LDA+GTB approach

TL;DR

This study uses an advanced LDA+GTB approach to analyze the doping dependence of band structure in Nd$_{2-x}$Ce$_x$CuO$_4$, revealing that many-body effects dominate over one-electron mechanisms in strongly correlated phases.

Contribution

It demonstrates that many-body effects are the primary factor influencing band structure changes with doping in Nd$_{2-x}$Ce$_x$CuO$_4$, using a combined LDA+GTB method.

Findings

Many-body effects dominate doping dependence in antiferromagnetic and paramagnetic phases.

One-electron mechanism has a minor role in band structure evolution.

Strong Coulomb repulsion significantly renormalizes quasiparticles.

Abstract

In the present work we report the band structure calculations for the high temperature superconductor Nd$_{2-x}$Ce$_x$CuO$_4$ in the regime of strong electronic correlations within an LDA+GTB method, which combines the local density approximation (LDA) and the generalized tight-binding method (GTB). The two mechanisms of band structure doping dependence were taken into account. Namely, the one-electron mechanism provided by the doping dependence of the crystal structure, and the many-body mechanism provided by the strong renormalization of the fermionic quasiparticles due to the large on-site Coulomb repulsion. We have shown that in the antiferromagnetic and in the strongly correlated paramagnetic phases of the underdoped cuprates the main contribution to the doping evolution of band structure and Fermi surface comes from the many-body mechanism.