Crossover from fragile to strong glassy behavior in kinetically constrained systems.
We show the existence of fragile-to-strong transitions in kinetically constrained systems by studying the equilibrium and out-of-equilibrium dynamics of a generic constrained Ising spin chain that interpolates between the symmetric and fully asymmetric cases. We find that for large but finite asymmetry the model displays a crossover from fragile to strong glassy behavior at finite temperature, which is controlled by the asymmetry parameter. The relaxation in the fragile region presents stretched exponential behavior, with a temperature dependent stretching exponent that is predicted. Our results are confirmed by numerical simulations.
Buhot
A
A
Theoretical Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP, United Kingdom. buhot@thphys.ox.ac.uk
Garrahan
J P
JP