paper

Monte Carlo Study of the S=1/2 and S=1 Heisenberg Antiferromagnet on a Spatially Anisotropic Square Lattice

arXiv:cond-mat/0004311 · doi:10.1103/PhysRevB.62.6378

Abstract

We present a quantum Monte Carlo study of a Heisenberg antiferromagnet on a spatially anisotropic square lattice, where the coupling strength in the x-direction () is different from that in the y-direction (). By varying the anisotropy from 0 to 1, we interpolate between the one-dimensional chain and the two-dimensional isotropic square lattice. Both and S=1 systems are considered separately in order to facilitate comparison. The temperature dependence of the uniform susceptibility and the spin-spin correlation length are computed down to very low temperatures for various values of . For S=1, the existence of a quantum critical point at as well as the scaling of the spin gap is confirmed. Universal quantities predicted from the nonlinear model agree with our results at without any adjustable parameters. On the other hand, the results are consistent with , as discussed by a number of previous theoretical studies. Experimental implications for compounds such as SrCuO are also discussed.

8 pages, 7 figures, to be published in Phys. Rev. B

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