Regular Article

Failure of the Schwinger boson approach in the description of the ground state in the spatially anisotropic Heisenberg model

Departamento de Física, Centro Federal de Educação Tecnológica de Minas Gerais, 30510-000, Belo Horizonte, MG, Brazil

^a e-mail: lslima@cefetmg.br

Received: 1 August 2018
Received in final form: 17 October 2018
Published online: 23 January 2019

Abstract

Density matrix renormalization group (DMRG) and Schwinger boson mean field theory (SBMFT) are used to study the behavior of the ground state energy in the integer spin two-dimensional anisotropic J_1x-J_1y-J₂ Heisenberg model in the square lattice with second neighbors interactions, where the influence of the critical parameters (D_c vs. J₂) have been verified on continuum spin conductivity (AC conductivity). We get a different behavior for the ground state energy using both methods, principally in the limit where the force of the parameters is larger, where the SBMFT theory is expected not to become accurate.