Ferromagnetism in the large-U Hubbard model

TL;DR

This paper investigates the emergence of ferromagnetism in the large-U Hubbard model on a hypercubic lattice using dynamical mean field theory, revealing conditions for ferromagnetic order and its thermodynamic properties.

Contribution

It introduces a detailed analysis of ferromagnetism in the large-U limit of the Hubbard model using DMFT and NCA, highlighting the phase diagram and magnetic behavior.

Findings

Ferromagnetic phase exists at large U values.

Curie temperature depends on Coulomb interaction strength.

Competition between ferromagnetism and antiferromagnetism is characterized.

Abstract

We study the Hubbard model on a hypercubic lattice with regard to the possibility of itinerant ferromagnetism. The Dynamical Mean Field theory is used to map the lattice model on an effective local problem, which is treated with help of the Non Crossing Approximation. By investigating spin dependent one-particle Green's functions and the magnetic susceptibility, a region with nonvanishing ferromagnetic polarization is found in the limit $U\to\infty$. The $\delta$-T-phase diagram as well as thermodynamic quantities are discussed. The dependence of the Curie temperature on the Coulomb interaction and the competition between ferromagnetism and antiferromagnetism are studied in the large $U$ limit of the Hubbard model.