Thermodynamic parameters of the<i>T=0</i>, spin-1/2 square-lattice Heisenberg antiferromagnet

Abstract

Transverse susceptibility (${\ensuremath{\chi}}_{\ensuremath{\perp}}$), spin stiffness constant (${\ensuremath{\rho}}_{s}$), spin-wave velocity (${c}_{s}$), staggered magnetization (${M}^{+}$) and the ground-state energy (${E}_{0}$) of the T=0, spin-(1/2 square-lattice Heisenberg antiferromagnet are estimated by expansions around the Ising limit. Extrapolations of the series, which take into account the leading singular behavior, give ${Z}_{\ensuremath{\chi}}$(=8${\ensuremath{\chi}}_{\ensuremath{\perp}}$J)=0.52\ifmmode\pm\else\textpm\fi{}0.03, (=4${\mathrm{\ensuremath{\rho}}}_{\mathrm{s}}$/J)=0.72 (=${\mathrm{c}}_{\mathrm{s}}$/ \ensuremath{\surd}2 J)=1.18\ifmmode\pm\else\textpm\fi{}0.02, 2${M}^{+}$=0.605\ifmmode\pm\else\textpm\fi{}0.015, and 4${E}_{0}$/J=-2.6785\ifmmode\pm\else\textpm\fi{}0.0010. The extrapolations are aided by universal amplitude ratios, whose values can be obtained exactly from the spin-wave theory.