By performing a high-statistics simulation of the D=4 random-field Ising model at zero temperature for different shapes of the random-field distribution, we show that the model is ruled by a single universality class. We compute to a high accuracy the complete set of critical exponents for this class, including the correction-to-scaling exponent. Our results indicate that in four dimensions (i) dimensional reduction as predicted by the perturbative renormalization group does not hold and (ii) three independent critical exponents are needed to describe the transition.
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http://dx.doi.org/10.1103/PhysRevLett.116.227201 | DOI Listing |
Entropy (Basel)
December 2024
Department of Civil, Environmental, Land, Building Engineering and Chemistry (DICATECh), Polytechnic University of Bari, Via Orabona 4, 70125 Bari, Italy.
Multi-stable behavior at the microscopic length-scale is fundamental for phase transformation phenomena observed in many materials. These phenomena can be driven not only by external mechanical forces but are also crucially influenced by disorder and thermal fluctuations. Disorder, arising from structural defects or fluctuations in external stimuli, disrupts the homogeneity of the material and can significantly alter the system's response, often leading to the suppression of cooperativity in the phase transition.
View Article and Find Full Text PDFPhys Rev E
October 2024
Institut für Theoretische Physik, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany and Department of Mathematics, King's College London, London WC2R 2LS, United Kingdom.
Amorphous solids can yield in either a ductile or brittle manner under strain: plastic deformation can set in gradually, or abruptly through a macroscopic stress drop. Developing a unified theory describing both ductile and brittle yielding constitutes a fundamental challenge of nonequilibrium statistical physics. Recently, it has been proposed that, in the absence of thermal effects, the nature of the yielding transition is controlled by physics akin to that of the quasistatically driven random field Ising model (RFIM), which has served as the paradigm for understanding the effect of quenched disorder in slowly driven systems with short-ranged interactions.
View Article and Find Full Text PDFPhys Rev E
July 2024
Department for Theoretical Physics, Jožef Stefan Institute, Sl-1001 Ljubljana, Slovenia.
Using numerical simulations, we investigate the impact of the demagnetization field and finite temperature on the hysteresis phenomena in disordered ferromagnetics systems. We model the behavior of thin systems employing the thermal nonequilibrium random field Ising model driven by a finite-driving rate protocol to study the shape of the hysteresis loop and demagnetization line and the magnetization fluctuations for varied parameters. Our results reveal a significant interplay of the disorder, the demagnetizing fields, and thermal fluctuations.
View Article and Find Full Text PDFNat Commun
August 2024
Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Jamming is an athermal transition between flowing and rigid states in amorphous systems such as granular matter, colloidal suspensions, complex fluids and cells. The jamming transition seems to display mixed aspects of a first-order transition, evidenced by a discontinuity in the coordination number, and a second-order transition, indicated by power-law scalings and diverging lengths. Here we demonstrate that jamming is a first-order transition with quenched disorder in cyclically sheared systems with quasistatic deformations, in two and three dimensions.
View Article and Find Full Text PDFNanomaterials (Basel)
June 2024
Forschungszentrum Jülich GmbH, Jülich Center for Neutron Scattering JCNS-1, Leo-Brandt Str., 52425 Jülich, Germany.
While Ising criticality in classical liquids has been firmly established both theoretically and experimentally, much less is known about criticality in liquids in which the growth of the correlation length is frustrated by finite-size effects. A theoretical approach for dealing with this issue is the random-field Ising model (RFIM). While experimental critical-exponent values have been reported for magnetic samples (here, we consider γ, ν and η), little experimental information is available for critical fluctuations in corresponding liquid systems.
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