### Abstract

Original language | English |
---|---|

Pages (from-to) | 4950–4958 |

Journal | Physica A: Statistical Mechanics and its Applications |

Volume | 388 |

Issue number | 24 |

DOIs | |

Publication status | Published - 22 Aug 2009 |

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### Bibliographical note

The full text is currently unavailable on the repository.### Keywords

- Quenched bond randomness
- Weak universality
- First-order transitions
- Triangular Ising model
- superantiferromagnetism
- Entropic sampling

### Cite this

*Physica A: Statistical Mechanics and its Applications*,

*388*(24), 4950–4958. https://doi.org/10.1016/j.physa.2009.08.022

**Criticality in the randomness-induced second-order phase transition of the triangular Ising antiferromagnet with nearest- and next-nearest-neighbor interactions.** / Fytas, Nikolaos G.; Malakis, A.

Research output: Contribution to journal › Article

*Physica A: Statistical Mechanics and its Applications*, vol. 388, no. 24, pp. 4950–4958. https://doi.org/10.1016/j.physa.2009.08.022

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TY - JOUR

T1 - Criticality in the randomness-induced second-order phase transition of the triangular Ising antiferromagnet with nearest- and next-nearest-neighbor interactions

AU - Fytas, Nikolaos G.

AU - Malakis, A.

N1 - The full text is currently unavailable on the repository.

PY - 2009/8/22

Y1 - 2009/8/22

N2 - Using a Wang–Landau entropic sampling scheme, we investigate the effects of quenched bond randomness on a particular case of a triangular Ising model with nearest- (Jnn) and next-nearest-neighbor (Jnnn) antiferromagnetic interactions. We consider the case R=Jnnn/Jnn=1, for which the pure model is known to have a columnar ground state where rows of nearest-neighbor spins up and down alternate and undergo a weak first-order phase transition from the ordered to the paramagnetic state. With the introduction of quenched bond randomness we observe the effects signaling the expected conversion of the first-order phase transition to a second-order phase transition and using the Lee–Kosterlitz method, we quantitatively verify this conversion. The emerging, under random bonds, continuous transition shows a strongly saturating specific heat behavior, corresponding to a negative exponent α, and belongs to a new distinctive universality class with ν=1.135(11), γ/ν=1.744(9), and β/ν=0.124(8). Thus, our results for the critical exponents support an extensive but weak universality and the emerged continuous transition has the same magnetic critical exponent (but a different thermal critical exponent) as a wide variety of two-dimensional (2d) systems without and with quenched disorder.

AB - Using a Wang–Landau entropic sampling scheme, we investigate the effects of quenched bond randomness on a particular case of a triangular Ising model with nearest- (Jnn) and next-nearest-neighbor (Jnnn) antiferromagnetic interactions. We consider the case R=Jnnn/Jnn=1, for which the pure model is known to have a columnar ground state where rows of nearest-neighbor spins up and down alternate and undergo a weak first-order phase transition from the ordered to the paramagnetic state. With the introduction of quenched bond randomness we observe the effects signaling the expected conversion of the first-order phase transition to a second-order phase transition and using the Lee–Kosterlitz method, we quantitatively verify this conversion. The emerging, under random bonds, continuous transition shows a strongly saturating specific heat behavior, corresponding to a negative exponent α, and belongs to a new distinctive universality class with ν=1.135(11), γ/ν=1.744(9), and β/ν=0.124(8). Thus, our results for the critical exponents support an extensive but weak universality and the emerged continuous transition has the same magnetic critical exponent (but a different thermal critical exponent) as a wide variety of two-dimensional (2d) systems without and with quenched disorder.

KW - Quenched bond randomness

KW - Weak universality

KW - First-order transitions

KW - Triangular Ising model

KW - superantiferromagnetism

KW - Entropic sampling

U2 - 10.1016/j.physa.2009.08.022

DO - 10.1016/j.physa.2009.08.022

M3 - Article

VL - 388

SP - 4950

EP - 4958

JO - Physica A: Statistical Mechanics and its Applications

JF - Physica A: Statistical Mechanics and its Applications

SN - 0378-4371

IS - 24

ER -