Tricritical behavior in a stacked triangular lattice Ising antiferromagnet CsCoBr3

CsCoBr3 is well described as a spin-1/2 Ising-like antiferromagnet (AF) on a stacked triangular lattice (STL). The combination of AF interactions and triangular coordination leads to geometrical frustration, which manifests itself in an unusual partially paramagnetic, long-range ordered state at low temperatures. We have studied both the order parameter as well as the fluctuations in the order parameter (the critical fluctuations), associated …