An entropy-driven noise-induced phase transition

We introduce a class of exactly solvable models which exhibit an ordering noise-induced phase transition driven by an entropic mechanism. In contrast with previous studies, order does not appear in this case as a result of an instability of the disordered phase produced by noise, but of a balance between the relaxing deterministic dynamics and the randomizing (entropic) character of the fluctuations. A finite-size scaling analysis of the phase transition reveals that it belongs to the universality class of the equilibrium Ising model. All these results are analyzed in the light of the nonequilibrium probability distribution of the system, which can be derived analytically. The relevance of our result as a possible scenario of the so-called Lower Critical Solution Temperature (LCST) transitions is analysed.