The finite-size properties of the square lattice quantum Heisenberg antiferromagnet

We study the spin-1/2 square lattice Heisenberg antiferromagnets with finite size by the nonlinear spin-wave theory At low temperatures, the effects of the lattice size (L x L) on the spin-wave velocity and the staggered magnetization are obtained, respectively We find that the staggered magnetization is very sensitive to the lattice size, while the finite size effect on the spin-wave velocity is weak. Moreover, the temperature dependence of the correlation length is also discussed. The results we have obtained are in agreement with the results of experiments and numerical simulations.