Non-equilibrium structures and slow dynamics in a two dimensional spin system with competitive long range and short range interactions

OMAR OSENDA; FRANCISCO A. TAMARIT; SERGIO A. CANNAS

PHYSICAL REVIEW E - STATISTICAL PHYSICS, PLASMAS, FLUIDS AND RELATED INTERDISCIPLINARY TOPICS

AMERICAN PHYSICAL SOCIETY

Año: 2009 vol. 80 p. 211141 - 2111413

1063-651X

We introduce a lattice spin model that mimics a system of interacting particles through a shortrange repulsive potential and a long range attractive power law decaying potential. We performa detailed analysis of the general equilibrium phase diagram of the model at finite temperature,showing that the only possible equilibrium phases are the ferromagnetic and the antiferromagneticones. We then study the non equilibrium behavior of the model after a quench to subcritical temperatures,in the antiferromagnetic region of the phase diagram region, where the pair interactionpotential behaves in the same qualitative way as in a Lennard-Jones gas. We find that, even inthe absence of quenched disorder or geometric frustration, the competition between interactionsgives rise to non–equilibrium disordered structures at low enough temperatures that strongly slowdown the relaxation of the system. This non–equilibrium state presents several features characteristicof glassy systems, such as subaging, non trivial Fuctuation Dissipation relations and possiblelogarithmic growth of free energy barriers to coarsening