Tricritical behavior in a stacked triangular lattice Ising antiferromagnetCsCoBr3

摘要: CsCoBr 3 is well described as a spin-½ Ising-like antiferromagnet (AF) on stacked triangular lattice (STL). The combination of AF interactions and 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 fluctuations (the critical fluctuations), associated with this magnetic phase transition T N =(28.23′0.04) K, high quality single crystal sample using neutron scattering techniques. Critical measurements were performed through two equivalent ordering wave vectors (-,-,1) (-,-,1). These are by single, anisotropic Lorentzian line shape over wide range about decades reduced temperature. characterized set three exponents ν=(0.54 ′ 0.05), γ=(1.05′0.08), β=(0.28′0.02), consistent scaling laws. results very close expectations tricritical behavior. They inconsistent from analytical theory Monte Carlo simulation relevant classical Ising model hexagonal isotropic interactions, predict that belongs 3D XY universality class. In light experimental results, we reexamined heat capacity same show these also