Softened spin-wave dispersion and sublattice magnetization at finite temperature for a three-dimensional anisotropic Heisenberg antiferromagnet

We study a three-dimensional anisotropic quantum antiferromagnetic Heisenbe rg model at finite temperature in which the interplanar coupling can be var ied gradually, With the magnon interactions considered, we have calculated the spin-wave excitation and sublattice magnetization. We find that when th e interplanar coupling increases, the Neel ordered state is stabilized grad ually. Moreover, we find power laws at low temperatures: a T-4-law for the spin-wave excitation, and a T-2-law for the sublattice magnetization, which is consistent with the nuclear magnetic resonance experiments on antiferro magnets. The interplanar coupling dependences of the finite-temperature spi n-wave excitation and magnetization are also given.