Experimental confirmation of the existence of a new universality class for stacked triangular lattices

Neutron scattering studies of CsMnBr3, a three-dimensional XY antiferromagnet on a stacked triangular lattice, have been carried out in the critical region. Measurements of three magnetic Bragg peak intensities as a function of temperature have shown that the transition to an antiferromagnetically ordered state at TN=8.3 K takes place with critical exponent beta =0.22+or-0.02. This value of beta does not correspond to any standard model of a …