Critical behavior of weakly diluted frustrated antiferromagnets

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Abstract
We study the effect of small amounts of bond or site dilution on some frustrated antiferromagnets (AF) in zero external field. We argue that random field (RF) like effects are generated by any small amounts of dilution in a large class of Ising AFs, and that these effects (1) are not covered by the criterion of Harris, (2) obliterate AF order in these systems for dd=2 quite likely), and (3) produce a reduced crossover temperature to impure critical behavior given by the tc∼(δJ)2/φ and φ≊γ (instead of φ=α prescribed by the criterion of Harris for random ferromagnets) for all fcc AF and some bcc AF. Our transfer matrix results for long strips support our arguments.