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Interplay between coarsening and nucleation in an Ising model with dipolar interactions
Sergio A Cannas1, Mateus F Michelon, Daniel A Stariolo
1Instituto de Física de la Facultad de Matemática, Astronomía y Física (IFFAMAF-CONICET), Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina. cannas@famaf.unc.edu.ar
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 31, 2008
Summary
This study explores the complex relaxation dynamics of a square lattice Ising model. The system exhibits competing stripe phases or a metastable nematic phase, revealing potential glassy behavior at low temperatures.
Area of Science:
- Condensed Matter Physics
- Statistical Mechanics
Background:
- The Ising model is a fundamental tool for studying magnetism and phase transitions.
- Understanding complex dynamical behaviors, such as metastability and coarsening, is crucial in statistical physics.
Purpose of the Study:
- To investigate the dynamical behavior of a square lattice Ising model with both exchange and dipolar interactions.
- To analyze the relaxation mechanisms, including coarsening and nucleation, after a temperature quench.
- To characterize the metastable nematic phase and its influence on the system's dynamics.
Main Methods:
- Monte Carlo simulations were employed to model the system's behavior.
- The distribution of equilibration times was measured for different relaxation pathways.
- Quasiequilibrium autocorrelations were computed across a range of temperatures.
Main Results:
- Two primary relaxation pathways were observed: direct coarsening into stripe phases or relaxation via a metastable nematic phase.
- The nematic phase exhibits strong metastability, influencing the decay to the equilibrium stripe phase.
- A distinct decay to a plateau in autocorrelations suggests frozen spins in the nematic phase, potentially a finite-size effect.
- Relaxation times in the metastable region display super-Arrhenius behavior, hinting at glassy dynamics.
Conclusions:
- The square lattice Ising model exhibits complex relaxation dynamics driven by competing stripe phases and a metastable nematic phase.
- The observed super-Arrhenius behavior in relaxation times suggests potential glassy characteristics at low temperatures.
- Further investigation into finite-size effects is warranted to fully understand the observed plateau in autocorrelations.
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