Crossover from fragile to strong glassy behavior in kinetically constrained systems

Area of Science:

• Condensed Matter Physics
• Statistical Mechanics
• Complex Systems

Background:

• Kinetically constrained systems exhibit complex dynamics.
• Understanding glassy behavior is crucial in statistical mechanics.
• Ising spin chains are fundamental models for magnetism and phase transitions.

Purpose of the Study:

• To demonstrate the existence of fragile-to-strong transitions in kinetically constrained systems.
• To investigate the equilibrium and out-of-equilibrium dynamics of a constrained Ising spin chain.
• To analyze the influence of asymmetry on glassy behavior.

Main Methods:

• Studying a generic constrained Ising spin chain model.
• Analyzing the model's dynamics across symmetric and asymmetric cases.
• Employing theoretical analysis and numerical simulations.

Main Results:

• Observed a crossover from fragile to strong glassy behavior at finite temperature for large but finite asymmetry.
• Identified the asymmetry parameter as the control for this transition.
• Characterized relaxation in the fragile region by stretched exponential behavior with a predicted temperature-dependent exponent.

Conclusions:

• The constrained Ising spin chain model successfully exhibits fragile-to-strong transitions.
• Asymmetry and temperature are key factors governing glassy dynamics in these systems.
• The findings provide insights into the nature of glassy states in kinetically constrained systems.