The ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model with spatially anisotropic couplings on a square lattice are investigated by a spin-rotation-invariant Green's-function approach and by Lanczos diagonalizations on lattices up to 36 sites supplemented by finite-size scaling. We focus on the anisotropy-driven transition from the N\'eel state to a paramagnetic state with antiferromagnetic short-range order and on the spatial dependence of spin correlation functions. Our principal result is that a rather sharp crossover in the magnetic behavior occurs at the coupling ratio R0≃0.2 (R=Jy/Jx).
@article{arxiv.cond-mat/9904005,
title = {Magnetic Order-Disorder Transition in the Two-Dimensional Spatially Anisotropic Heisenberg Model at Zero Temperature},
author = {D. Ihle and C. Schindelin and A. Weisse and H. Fehske},
journal= {arXiv preprint arXiv:cond-mat/9904005},
year = {2007}
}