Critical Behavior of the Three-Dimensional Dilute Ising Antiferromagnet in a Field

Abstract

We report results of large Monte Carlo simulations of an experimentally realizable random-field system: the three-dimensional dilute Ising antiferromagnetic in a field. We find that the correlation time diverges dramatically as $T\ensuremath{\rightarrow}{T}_{c}$; the results are consistent with a proposed new type of activated dynamic scaling. The transition appears to be continuous, with effective critical exponents $\ensuremath{\eta}=0.5\ifmmode\pm\else\textpm\fi{}0.1$ and $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\eta}}=\ensuremath{-}1.0\ifmmode\pm\else\textpm\fi{}0.3$ for strong fields, away from the weak-field regime where crossover effects distort exponent estimates. These strong-field exponents satisfy recently derived inequalities.