Phase Transitions in a Disordered System in and out of Equilibrium

Colaiori, Francesca; Alava, Mikko J.; Durin, Gianfranco; Magni, A.; Zapperi, Stefano

doi:10.1103/physrevlett.92.257203

Cited by 19 publications

(26 citation statements)

References 35 publications

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“…However, it is clear that this transition, with its coexistence of second-order-like critical behavior measured to very small reduced temperatures as well as severe hysteresis upon temperature reversals near the phase boundary, is highly unusual. It is not correct to assume that simply not being in equilibrium would account for different critical behavior [37]. It is likely that such behavior is more generic in systems undergoing phase transitions in the presence of quenched disorder.…”

Section: Resultsmentioning

confidence: 99%

Quasistationary criticality of the order parameter of the three-dimensional random-field Ising antiferromagnetFe0.85Zn0.15F2: A synchrotron x-ray scattering study

Zhou

Meyer

et al. 2006

Phys. Rev. B

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The critical exponent β = 0.17 ± 0.01 for the three-dimensional random-field Ising model (RFIM) order parameter upon zero-field cooling (ZFC) has been determined using extinction-free magnetic x-ray scattering techniques for Fe0.85Zn0.15F2. This result is consistent with other exponents determined for the RFIM in that Rushbrooke scaling is satisfied. Nevertheless, there is poor agreement with equilibrium computer simulations, and the ZFC results do not agree with field-cooling (FC) results. We present details of hysteresis in Bragg scattering amplitudes and line shapes that help elucidate the effects of thermal cycling in the RFIM, as realized in dilute antiferromagnets in an applied field. We show that the ZFC critical-like behavior is consistent with a second-order phase transitions, albeit quasi-stationary rather than truly equilibrium in nature, as evident from the large thermal hysteresis observed near the transition.

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Section: Resultsmentioning

confidence: 99%

Quasistationary criticality of the order parameter of the three-dimensional random-field Ising antiferromagnetFe0.85Zn0.15F2: A synchrotron x-ray scattering study

Zhou

Meyer

et al. 2006

Phys. Rev. B

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“…6,9,13 ͑Additional, but less conclusive evidence is provided by exact, but mean-field-like results on the Bethe lattice 13 and by perturbation theory near the upper critical dimension d =6.…”

Section: Discussionmentioning

confidence: 99%

“…If so, will the critical behavior be the same as with the single-spin-flip dynamics? There is in fact the intriguing possibility, supported by numerical simulations and analytical arguments, 6,9,12,13 that the nonequilibrium and equilibrium transitions of the T = 0 RFIM belong to the same universality class, even if criticality occurs in zero external field at equilibrium and at a nonzero coercive field in the irreversible evolution.…”

Section: Introductionmentioning

confidence: 99%

Hysteresis and avalanches in theT=0random-field Ising model with two-spin-flip dynamics

2005

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We study the nonequilibrium behavior of the three-dimensional Gaussian random-field Ising model at T = 0 in the presence of a uniform external field using a two-spin-flip dynamics. The deterministic, historydependent evolution of the system is compared with the one obtained with the standard one-spin-flip dynamics used in previous studies of the model. The change in the dynamics yields a significant suppression of coercivity, but the distribution of avalanches ͑in number and size͒ stays remarkably similar, except for the largest ones that are responsible for the jump in the saturation magnetization curve at low disorder in the thermodynamic limit. By performing a finite-size scaling study, we find strong evidence that the change in the dynamics does not modify the universality class of the disorder-induced phase transition.

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“…In the former case, the free surface of a sys- tem at T Ͼ 0 is in analogy with the zero-temperature 3D RFIM case inherently disordered ͑the 2D spin glass has a T = 0 phase transition͒. In the second case, the situation is much more akin to the one at hand, 27 and one should consider as the order parameter the remanent surface magnetization after a demagnetization procedure.…”

Section: Discussionmentioning

confidence: 99%

“…27, also for experimental suggestions͒. Two evident possibilities are looking for the same phenomenology in 3D Ising spin glasses, and in the 3D zero-temperature nonequilibrium RFIM.…”

Section: Discussionmentioning

confidence: 99%

Surface criticality in random field magnets

Laurson

Alava

2005

Phys. Rev. B

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The boundary-induced scaling of three-dimensional random field Ising magnets is investigated close to the bulk critical point by exact combinatorial optimization methods. We measure several exponents describing surface criticality: ␤ 1 for the surface layer magnetization and the surface excess exponents for the magnetization and the specific heat, ␤ s and ␣ s . The latter are related to the bulk phase transition by the same scaling laws as in pure systems, but only with the same violation of the hyperscaling exponent as in the bulk. The boundary disorders faster than the bulk, and the experimental and theoretical implications are discussed.

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Phase Transitions in a Disordered System in and out of Equilibrium

Cited by 19 publications

References 35 publications

Quasistationary criticality of the order parameter of the three-dimensional random-field Ising antiferromagnetFe0.85Zn0.15F2: A synchrotron x-ray scattering study

Quasistationary criticality of the order parameter of the three-dimensional random-field Ising antiferromagnetFe0.85Zn0.15F2: A synchrotron x-ray scattering study

Hysteresis and avalanches in theT=0random-field Ising model with two-spin-flip dynamics

Surface criticality in random field magnets

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