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Fluctuations in the time variable and dynamical heterogeneity in glass-forming systems
Karina E Avila1, Horacio E Castillo, Azita Parsaeian
1Department of Physics and Astronomy and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA and Max-Planck-Institut für Dynamik und Selbstorganisation, Am Fassberg 17, D-37077 Göttingen, Germany.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 16, 2013
Summary
Dynamical heterogeneity in glasses originates from soft modes linked to broken time-reparametrization symmetry. These fluctuations dominate at low temperatures and long timescales, confirming the hypothesis.
Area of Science:
- Condensed Matter Physics
- Statistical Mechanics
- Soft Matter Physics
Background:
- Dynamical heterogeneity is a key feature of slowly relaxing systems like structural glasses.
- Its microscopic origin remains a significant challenge in condensed matter physics.
Purpose of the Study:
- To test the hypothesis that dynamical heterogeneity arises from soft (Goldstone) modes associated with broken continuous symmetry under time reparametrizations.
- To investigate the relationship between these soft modes and observable dynamical heterogeneity.
Main Methods:
- Constructing coarse-grained observables from simulation data of four structural glass models.
- Decomposing fluctuations into transverse (soft mode) and longitudinal components.
- Analyzing the temperature and timescale dependence of these components.
Main Results:
- Time-reparametrization fluctuations (transverse components) increase in dominance as temperature decreases and timescales lengthen.
- The ratio of transverse to longitudinal fluctuation strengths grows with dynamical susceptibility (χ(4)).
- Correlation volumes of transverse fluctuations scale with dynamical heterogeneity, while longitudinal correlations remain small and constant.
Conclusions:
- The study provides strong evidence supporting the hypothesis linking dynamical heterogeneity to time-reparametrization soft modes.
- This finding offers a new theoretical framework for understanding the dynamics of glassy systems.
- The results have implications for materials science and the development of novel glassy materials.
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