Extended Hubbard model in the presence of a magnetic field

TL;DR

This paper provides an exact solution to the one-dimensional extended Hubbard model with magnetic field, revealing multiple phases, charge orderings, and magnetic effects on thermodynamic properties in the narrow band limit.

Contribution

It presents the first exact solution of the extended Hubbard model with magnetic field in one dimension, highlighting phase transitions and magnetic phenomena.

Findings

Existence of four phases in (U, n, h) space with phase transitions.

Magnetic field induces magnetization plateaus and modifies specific heat structure.

Critical fields lead to full or partial polarization depending on particle density.

Abstract

Within the Green's function and equations of motion formalism it is possible to exactly solve a large class of models useful for the study of strongly correlated systems. Here, we present the exact solution of the one-dimensional extended Hubbard model with on-site $U$ and first nearest neighbor repulsive V interactions in the presence of an external magnetic field h, in the narrow band limit. At zero temperature our results establish the existence of four phases in the three-dimensional space (U, n, h) - n is the filling - with relative phase transitions, as well as different types of charge ordering. The magnetic field may dramatically affect the behavior of thermodynamic quantities, inducing, for instance, magnetization plateaus in the magnetization curves, and a change from a single to a double-peak structure in the specific heat. According to the value of the particle density, we find one or two critical fields, marking the beginning of full or partial polarization. A detailed study of several thermodynamic quantities is also presented at finite temperature.