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Article Dans Une Revue Condensed Matter Physics Année : 2014

Stability of the Griffiths phase in the 2D Potts model with correlated disorder

Christophe Chatelain

Résumé

A Griffiths phase has recently been observed by Monte Carlo simulations in the 2D $q$-state Potts model with strongly correlated quenched random couplings. In particular, the magnetic susceptibility was shown to diverge algebraically with the lattice size in a broad range of temperatures. However, only relatively small lattice sizes could be considered so one can wonder whether this Griffiths phase will not shrink and collapse into a single point, the critical point, as the lattice size is increased to much larger values. In this paper, the 2D eight-state Potts model is numerically studied for four different disorder correlations. It is shown that the Griffiths phase cannot be explained as a simple spreading of local transition temperatures caused by disorder fluctuations. As a consequence, the vanishing of the latter in the thermodynamic limit does not necessarily imply the collapse of the Griffiths phase into a single point. In contrast, the width of the Griffiths phase is controlled by the disorder strength. However, for disorder correlations decaying slower than $1/r$, no cross-over to a more usual critical behavior could be observed as this strength is tuned to weaker values.
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Dates et versions

hal-00983707 , version 1 (25-04-2014)
hal-00983707 , version 2 (24-11-2014)

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Christophe Chatelain. Stability of the Griffiths phase in the 2D Potts model with correlated disorder. Condensed Matter Physics, 2014, 17 (3), pp.33601. ⟨10.5488/CMP.17.33601⟩. ⟨hal-00983707v1⟩
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