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Monte Carlo study of the two-dimensional spin-1/2 quantum Heisenberg model: Spin correlations in La/sub 2/CuO/sub 4/

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)
We study the spin-1/2 quantum ferromagnetic and antiferromagnetic Heisenberg model using Handscomb's Monte Carlo (MC) method on square lattices of various sizes. As the temperature is lowered the calculated correlation length in the antiferromagnetic case grows more rapidly than in the ferromagnetic case. We also obtain the correlation length in the leading order of the high-temperature series expansion which, at high temperatures, agrees very well with the MC results. The correlation length obtained from the MC calculation for the ferromagnetic and antiferromagnetic case is compared with existing theories. Taking the average value for the antiferromagnetic coupling between the values suggested by neutron- and Raman-scattering experiments done on La/sub 2/CuO/sub 4/, we compare our results for the correlation length with those observed by the neutron-scattering experiments. We find that our results for the correlation lengths away from the three-dimensional (3D) Neel temperature T/sub N/approx.200 K are consistent with the experimental findings. In order to obtain agreement close to the Neel temperature, however, we need to introduce an interlayer coupling between the CuO/sub 2/ planes. The effect on a 3D coupling is only discussed in the framework of the quantum mechanical nonlinear sigma model in three space dimensions. For the case of La/sub 2/CuO/sub 4/ we find that close to T/sub N/ the sigma model in 3+1 dimensions reduces to the classical 3D Heisenberg model whose critical properties are known and fit the neutron-scattering data for Tapprox.T/sub N/.
Research Organization:
Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306
OSTI ID:
6441449
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 39:1; ISSN PRBMD
Country of Publication:
United States
Language:
English