1997/09/16 by C. Lavalle, Sandro Sorella, S. Sorella +2 · 4 citations
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Theoretical and Computational Physics #cond-mat
paper · pdf · doi:10.1103/physrevlett.80.1746
4 pages, RevTeX + 5 encapsulated postscript figures
arxiv created 1997/09/16 · openalex publication_date 1998/02/23 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We study the low energy spectrum of the nearest neighbor Heisenberg model on a square lattice as a function of the total spin S. By quantum Monte Carlo simulation we compute this spectrum for Heisenberg models with local moments s\phantom\rule0ex0ex=\phantom\rule0ex0ex1/2, s\phantom\rule0ex0ex=\phantom\rule0ex0ex1, and s\phantom\rule0ex0ex=\phantom\rule0ex0ex3/2. We conclude that the nonlinear \ensuremathσ model prediction for the low energy spectrum is always verified for a large enough system size. However, the crossover to the correct scaling regime is particularly slow just for the s\phantom\rule0ex0ex=\phantom\rule0ex0ex1/2 Heisenberg model. The possible detection of this unexpected anomaly with finite temperature experiments on s\phantom\rule0ex0ex=\phantom\rule0ex0ex1/2 isotropic quantum antiferromagnets is also discussed.