Heuristic treatments of tricritical behaviour as observed in 4He–3He mixtures and in polymeric assemblies

Abstract

Tricritical behaviour in three dimensions is accessible to experiment in, for example, 4He–3He mixtures and some polymeric assemblies. Here, by largely heuristic arguments, which appeal however to some specific model Hamiltonians, we indicate how one can understand the gist of the experimental results near the tricritical point in the systems cited above. We point out that the spin fluctuations at the tricritical point are much weaker than those at the critical point, which leads to the conclusion that the tricritical behaviours can be described well by the mean-field exponents with logarithmic corrections, at d = 3.