Quantum fluctuation in a two-dimensional Heisenberg antiferromagnet at zero temperature

Abstract

Quantum correction to the dynamical spin-correlation functions are calculated up to 1/(2 S) 2 in a two-dimensional Heisenberg antiferromagnet at zero temperature by using the Holstein-Primakoff transformation. It is shown that the second-order correction gives rise to a large intensity of the sideband corresponding to three-magnon excitations, decreasing the intensity of the spin-wave peak. Renormalization factors are also calculated of the spin-wave velocity, the sublattice magnetization, the perpendicular susceptibility, and the spin-stiffness constant.