arXiv:cond-mat/0301526 · Physical review. B, Condensed matter
Critical dynamics of the simple-cubic Heisenberg antiferromagnet RbMnF3: Extrapolation to q=0
Shan-Ho Tsai, David Paul Landau
Abstract
Monte Carlo and spin dynamics simulations have been used to study the dynamic critical behavior of ${\mathrm{RbMnF}}_{3},$ treated as a classical Heisenberg antiferromagnet on a simple cubic lattice. In an attempt to understand the difference in the value of the dynamic critical exponent z between experiment and theory, we have used larger lattice sizes than in our previous simulations to better probe the asymptotic critical region in momentum. We estimate $z=1.49\ifmmode\pm\else\textpm\fi{}0.03,$ in good agreement with the renormalization-group theory and dynamic scaling predictions. In addition, the central peak in the dynamic structure factor at ${T}_{c},$ seen in experiments and previous simulations, but absent in the renormalization-group and mode-coupling theories, is shown to be solely in the longitudinal component.