Fermionic systems with charge correlations on the Bethe lattice

Abstract

A fermionic model, built up of q species of localized Fermi particles, interacting by charge correlations, is isomorphic to a spin-q/2 Ising model. However, the equivalence is only formal and the two systems exhibit a different physical behavior. By considering a Bethe lattice with q=1, we have exactly solved the models. There exists a critical temperature below which there is a spontaneous breakdown of the particle-hole symmetry for the first model, and of the spin symmetry for the second. While the spin system is always stable and exhibits a homogeneous ferromagnetic phase below T_{c}, the fermionic system for T<T_{c} is unstable against the formation of inhomogeneous phases with charge separation.

2 pages, 4 figures

References in corpus (5)

• The Hubbard model within the equations of motion approach
• Exact solution of the one-dimensional spin-$\frac{3}{2}$ Ising model in magnetic field
• Fermionic systems with charge correlations
• Equations of motion approach to the spin-1/2 Ising model on the Bethe lattice
• New perspectives on the Ising model