Extended Schwinger-Boson theory of the two-dimensional spin-1/2 anisotropic Heisenberg antiferromagnets

Abstract

An extended Schwinger-boson mean-field theory based on the symmetry considerations is developed to study the zero-temperature properties of the two-dimensional anisotropic spin-1/2 Heisenberg antiferromagnets. The Bose condensation of the Schwinger bosons occurring in different fashions at various anisotropies is shown to provide a natural description of the variation of spin long range antialignment with the anisotropy. The ground state energy and the excitation spectra are found consistent with the numerical results both in the XY-like and the Ising-like anisotropic systems.