Toldin, F. Parisen and Pelissetto, A. and Vicari, E. (2009) *Strong-disorder paramagnetic-ferromagnetic fixed point in the square-lattice +- J Ising model.* Journal of Statistical Physics, 135 . p. 1039. ISSN 0022-4715

## Abstract

We consider the random-bond +- J Ising model on a square lattice as a function of the temperature T and of the disorder parameter p (p=1 corresponds to the pure Ising model). We investigate the critical behavior along the paramagnetic-ferromagnetic transition line at low temperatures, below the temperature of the multicritical Nishimori point at T*= 0.9527(1), p*=0.89083(3). We present finite-size scaling analyses of Monte Carlo results at two temperature values, T=0.645 and T=0.5. The results show that the paramagnetic-ferromagnetic transition line is reentrant for T<T*, that the transitions are continuous and controlled by a strong-disorder fixed point with critical exponents nu=1.50(4) and eta=0.128(8), and beta = 0.095(5). This fixed point is definitely different from the Ising fixed point controlling the paramagnetic-ferromagnetic transitions for T>T*. Our results for the critical exponents are consistent with the hyperscaling relation 2 beta/nu - eta = d - 2 = 0.

Item Type: | Article |
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Additional Information: | Imported from arXiv |

Subjects: | Area02 - Scienze fisiche > FIS/02 - Fisica teorica, modelli e metodi matematici |

Divisions: | Dipartimenti (until 2012) > DIPARTIMENTO DI FISICA " E. FERMI" |

Depositing User: | dott.ssa Sandra Faita |

Date Deposited: | 09 Apr 2015 16:20 |

Last Modified: | 09 Apr 2015 16:20 |

URI: | http://eprints.adm.unipi.it/id/eprint/1858 |

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