Excitations and finite-size properties of an integrable supersymmetric electronic model

Abstract

We investigate the bulk and finite-size properties of an integrable extension of the Hubbard model with a free parameter γ related to the quantum deformation of the superalgebra sl (2|2)(2). The Bethe ansatz solution is used to determine the ground state and the nature of the spin and charge excitations. As γ→0 the charge dispersion relation for low momenta crossover from linear to parabolic foreseeing a change from antiferromagnetic to ferromagnetic behavior. The study of the finite-size corrections to the spectrum reveals us that the underlying conformal theory has central charge c=-1 and a related effective central charge cef =2 as well as critical exponents depending on the parameter γ. We note that exact results at the isotropic point γ=0 can be established without recourse to the Bethe ansatz solution. © 2010 The American Physical Society.