Specific-heat critical behavior of the Ising stacked triangular lattice antiferromagnet CsCoBr3.

We have measured the specific-heat critical behavior of the Ising stacked triangular lattice antiferromagnet CsCoBr[sub 3], an excellent example of a fully frustrated three-dimensional second-order phase transition. For the transition near [ital T]=28 K, [alpha]=[minus]0.025[plus minus]0.004 and [ital A][sup +]/[ital A][sup [minus]]=1.07[plus minus]0.02 are consistent both with predicted [ital d]=3 [ital XY] criticality and Monte Carlo simulations which indicate critical behavior close to, but distinct from [ital XY] universality. No latent heat is observed, consistent with a second-order transition. No specific-heat peak is observed at the transitions reported at lower temperatures.