Multiscale Relaxation Dynamics in Ultrathin Metallic Glass-Forming Films
Thedensitylayeringphenomenonoriginatingfromafreesurfacegivesrisetothelayerlikedynamicsand stress heterogeneity in ultrathin Cu-Zr glassy films, which facilitates the occurrence of multistep relaxations in the timescale of computer simulations. Taking advantage of this condition, we trace the relaxation decoupling and evolution with temperature simply via the intermediate scattering function. We show that the β relaxation hierarchically follows fast and slow modes in films, and there is a β-relaxation transition as the film is cooled close to the glass transition. We provide the direct observation of particle motions responsible for the β relaxation and reveal the dominant mechanism varying from the thermal activated to the cooperative jumps across the transition.
Revealing the Link between Structural Relaxation and Dynamic Heterogeneity in Glass-Forming Liquids
Despite the use of glasses for thousands of years, the nature of the glass transition is still mysterious. On approaching the glass transition, the growth of dynamic heterogeneity has long been thought to play a key role in explaining the abrupt slowdown of structural relaxation. However, it still remains elusive whether there is an underlying link between structural relaxation and dynamic heterogeneity. Here, we unravelthelinkbyintroducingacharacteristictimescalehidingbehindanidenticaldynamicheterogeneity for various model glass-forming liquids. We find that the time scale corresponds to the kinetic fragility of liquids. Moreover, it leads to scaling collapse of both the structural relaxation time and dynamic heterogeneity for all liquids studied, together with a characteristic temperature associated with the same dynamicheterogeneity.Ourfindingsimplythatstudyingtheglasstransitionfromtheviewpointofdynamic heterogeneity is more informative than expected.
PRL18-Multiscale Relaxation Dynamics in Ultrathin MG.pdf
PRL18-Relaxation-heterogeneity in MG.pdf