Phase Transition of the Three-DimensionalXYAntiferromagnet on the Layered-Triangular Lattice

Phase transition of the frustrated X Y (plane rotator) antiferromagnet on the three-dimensional layered-triangular lattice is studied with use of a symmetry argument and a Monte Carlo simulation. A second-order transition of a new universality class is found with the exponents α≃0.44, β≃0.22, γ≃1.1 and ν≃0.52. Certain types of canted or helical magnets are predicted to belong to the same universality class.