Spherical Symmetric Spin Wave Theory of Heisenberg Model

Abstract

We represent simple decoupling scheme for two-time spin Green’s function which leads to the rotational invariant spin wave theory for low dimensional Heisenberg magnetics without broken symmetry and with correct sum rule \hatS_r²=S(S+1). For two-dimensional S=1⁄2 antiferromagnet this theory predicts disodered ground state while for S>1⁄2 it possesses long range order at T=0. The dynamic structure factor is calculated.