SELF-CONSISTENT SPIN-WAVE APPROACH TO THE 2-DIMENSIONAL SPATIALLY ANISOTROPIC HEISENBERG-ANTIFERROMAGNET

The ground-state properties of the S=1/2 spatially anisotropic Heisenberg antiferromagnet on the square lattice are investigated by use of the self-consistent spin-wave approach, in which the effect of kinematical interaction between spin waves is taken into account seriously. In terms of an anisotropic parameter lambda, our result can be expressed as follows: At finite lambda, Neel-ordered ground state is always stabilized and only in the limit of vanishing lambda, a disordered ground state can be realized, where lambda=1 corresponds to spatially isotropic case and lambda=0 to extremely anisotropic case in which the system becomes spin chains. The present result is in contradiction to the recent work of Parola, Sorella and Zhong, but in agreement with the one of Sakai and Takahashi based on the interchain mean-field theory.