The study of magnetic properties of the quasi-one-dimensianal spin-1/2 antiferromagnet by Monte-Carlo method

The thermodynamic quantities, two- and four-spin correlation functions as w ell as the correlation radius for weakly coupled antiferromagnetic spin cha ins with S = 1/2 are calculated using the mean-field approximation for the interchain coupling (J(2)) for longitudinal and transverse spin components by quantum Monte Carlo method. Results for the staggered magnetization and Neel temperature are in agreement with general scaling arguments. The value of triplet DeltaS(z) =1 gp in the spectrum of excitations is estimated. Th e transverse staggered field was found to induce an additional maximum in t he correlation radius of the four spin correlation function around T/J(1) a pproximate to [0.05 divided by 0.075), J(2)/J(1) > 0.03.