Spontaneous ordering against an external field in non-equilibrium systems

Abstract

We study the collective behavior of nonequilibrium systems subject to an\nexternal field with a dynamics characterized by the existence of\nnon-interacting states. Aiming at exploring the generality of the results, we\nconsider two types of models according to the nature of their state variables:\n(i) a vector model, where interactions are proportional to the overlap between\nthe states, and (ii) a scalar model, where interaction depends on the distance\nbetween states. In both cases the system displays three phases: two ordered\nphases, one parallel to the field, and another orthogonal to the field; and a\ndisordered phase. The phase space is numerically characterized for each model\nin a fully connected network. By placing the particles on a small-world\nnetwork, we show that, while a regular lattice favors the alignment with the\nfield, the presence of long-range interactions promotes the formation of the\nordered phase orthogonal to the field.\n