Quantum renormalizations in the spin-1 Heisenberg antiferromagnet on the square lattice

The renormalized parameters, characterizing the static and dynamic low-temperature properties of the spin-1 Heisenberg antiferromagnet on the square lattice, are estimated by expansions around the Ising limit. The calculations include the renormalization of the perpendicular susceptibility (${\mathrm{\chi }}_{\mathrm{\perp }}$) and the frequency moments of the inelastic light scattering spectra from spin-pair excitations. The results are used to assess the quantitative accuracy of the spin-wave calculations of Oguchi for ${\mathrm{\chi }}_{\mathrm{\perp }}$ and the two-magnon calculation of Parkinson for the light scattering spectra. They are found to be in agreement with experiments on ${\mathrm{K}}_2$ ${\mathrm{NiF}}_4$.