Aging exponents for nonequilibrium dynamics following quenches from critical points

Area of Science:

• Statistical Physics
• Condensed Matter Physics
• Computational Physics

Background:

• Studying nonequilibrium dynamics is crucial for understanding systems far from equilibrium.
• The Ising model is a fundamental model for magnetism and phase transitions.
• Nonequilibrium universality classes describe the large-scale behavior of systems after a rapid change.

Purpose of the Study:

• To quantify nonequilibrium universality classes in the Ising model.
• To investigate the effect of initial configurations (correlated vs. uncorrelated) on dynamics.
• To determine the decay exponents of the order-parameter autocorrelation function.

Main Methods:

• Monte Carlo simulations were employed to model the nearest-neighbor Ising model.
• Quenches were performed to points within the ordered region of the phase diagram.
• Analysis focused on the decay of the order-parameter autocorrelation function and exponent quantification.

Main Results:

• Exponents (λ) for aging dynamics were quantified for both conserved and nonconserved dynamics in d=3.
• A bound was demonstrated to be satisfied by these exponents via structural analysis.
• Results for d=2 were revisited, yielding more accurate exponent values.
• The exponent λ was found to be approximately invariant between conserved and nonconserved dynamics, irrespective of dimension.

Conclusions:

• The study provides quantitative insights into nonequilibrium universality classes.
• Aging dynamics in the Ising model exhibit dimensional and dynamical (conserved/nonconserved) independence for the exponent λ.
• The findings contribute to a deeper understanding of systems evolving far from equilibrium.