1,721,131 research outputs found
Clusters and droplets in the q-state Potts model
No full textA Potts correlated polychromatic percolation is studied. The clusters are made of sites corresponding to a given value of the q-state Potts variables, connected by bonds being active with probability pB. To treat this problem an s-state Potts Hamiltonian diluted with q-state Potts variables (instead of lattice gas variables) is introduced to which the the Migdal-Kadanoff renormalisation group is applied. It is found for a particular choice of pB=1-e-K (where K is the Potts coupling constant divided by the Boltzmann factor) that these clusters, called droplets diverge at the Potts critical point with Potts exponents
Macroscopic glassy relaxations and microscopic motions in a Frustrated Lattice Gas
No full textWe study microscopic and macroscopic dynamical properties of a frustrated lattice gas showing the violation of Stokes-Einstein law. Its glassy behaviors are analyzed and related with experimental results in glass former systems
Percolation transition in spin glasses
No full textThe percolation properties of geometrical clusters related to spin fluctuations have been investigated for the 3d ± J Ising spin glass. The percolation transition is found at a temperature Tp ~= 3.92, far from the spin glass critical temperature. The critical exponents are consistent with the random percolation exponents
Density fluctuations in a model for vibrated granular media
No full textThis paper investigates density fluctuations in a model for vibrated granular media. Their microscopic origin is shown to be linked to the microscopic disorder in grains packing
Dynamical heterogeneities in the crossover region from colloidal gels to colloidal glasses
No full textNonexponential relaxation in fully frustrated models
No full textWe study the dynamical properties of the fully frustrated Ising model. Due to the absence of disorder the model, contrary to spin glass, does not exhibit any Griffiths phase, which has been associated to nonexponential relaxation dynamics. Nevertheless, we find numerically that the model exhibits; a stretched exponential behavior below a temperature T-p corresponding to the percolation transition of the Kasteleyn-Fortuin clusters. We have also found that the critical behavior of these clusters for a fully frustrated q-state spin model at the percolation threshold is strongly affected by frustration. In fact while in the absence of frustration the q=1 limit gives random percolation. in the presence of frustration the critical behavior is in the same universality class of the ferromagnetic q=1/2-state Potts model
Self-tuning phase separation in a model with competing interactions inspired by biological cell polarization
No full textWe present a theoretical study of a system with competing short-range ferromagnetic attraction and a
long-range antiferromagnetic repulsion, in the presence of a uniform external magnetic field. The interplay
between these interactions, at sufficiently low temperature, leads to the self-tuning of the magnetization to a
value which triggers phase coexistence, even in the presence of the external field. The investigation of this
phenomenon is performed using a Ginzburg-Landau functional in the limit of an infinite number of order
parameter components large N model. The scalar version of the model is expected to describe the phase
separation taking place on a cell surface when this is immersed in a uniform concentration of chemical
stimulant. A phase diagram is obtained as a function of the external field and the intensity of the long-range
repulsion. The time evolution of the order parameter and of the structure factor in a relaxation process is
studied in different regions of the phase diagram
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