Local properties of the t-J model in a two-pole approximation within COM

TL;DR

This paper investigates the t-J model using a two-pole approximation within the composite operator method, providing a computationally efficient way to analyze magnetic correlations and system parameters.

Contribution

It introduces a novel two-pole approximation approach within COM, enabling accurate analysis of the t-J model with less computational effort.

Findings

Good agreement with exact numerical methods

Anti-ferromagnetic correlations decrease with doping

Temperature and exchange effects analyzed

Abstract

In this work, we study the t-J model using a two-pole approximation within the composite operator method. We choose a basis of two composite operators -- the constrained electrons and their spin-fluctuation dressing -- and approximate their currents in order to compute the corresponding Green's functions. We exploit the algebraic constraints obeyed by the basis operators to close a set of self-consistent equations that is numerically solved. This allows to determine the physical parameters of the system such as the spin-spin correlation function and the kinetic energy. Our results are compared to those of an exact numerical method on a finite system to asses their reliability. Indeed, a very good agreement is achieved through a far less numerically demanding and a more versatile procedure. We show that by increasing the hole doping, anti-ferromagnetic correlations are replaced by ferromagnetic ones. The behavior on changing temperature and exchange integral is also studied and reported.