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 $T\to T_c$; the results are consistent with a proposed new type of activated dynamic scaling. The transition appears to be continuous, with effective critical exponents $\eta =0.5\mathrm{}\pm 0.1$ and $\tilde{\eta }=-1.0\mathrm{}\pm 0.3$ for strong fields, away from the weak-field regime where crossover effects distort exponent estimates. These strong-field exponents satisfy recently derived inequalities.