Extreme fluctuations driving the relaxation in glassy energy landscapes

Real-space model for activated processes in rejuvenation and memory behavior of glassy systems

“…) Ultimately, this heterogeneity is exactly what is captured by the break-up of clusters in our model, after coarsegraining out the in-cage rattle, as that rattle only rarely amounts to meaningful (record-sized, irreversible) displacements. 32…”

“…There, a hierarchy of barriers emerges that quite naturally calls for an effective description of the ensuing dynamics in terms of a sequence of activated events that is called record dynamics (RD), 29 since that hierarchy renders all but the largest fluctuations ineffectual and relaxation is characterized by timescales for barrier crossings that exceed all others. 9,[30][31][32] There is significant experimental evidence indicating the dominance of such large, intermittent events in driving the relaxation dynamics. 10,11,26,[33][34][35][36][37] Alternative approaches to describe aging in terms of intermittent events.…”

“…Accordingly, in RD incremental relaxation is coarse-grained into a sequence of record barrier crossing events that are required to unlock farther reaches in the landscape. 32,39 These records drive the dynamics (i.e., ''set the clock'') in disordered materials, generically, reminiscent of the concept of ''material time''. 40,41 This ''clock'' for records decelerates at a rate l(t) p 1/t, as new records are ever harder to achieve.…”

Density fluctuations in granular piles traversing the glass transition: A grain-scale characterization via the internal energy

“…Whether the transition was approached gradually or via a hardquench in the intensity of taps, we encountered the same phenomenology in the granular pile as is observed for other glass-forming materials. Although the distribution of fluctuations elicited by a perturbation within a granular medium may have profound differences to conventional thermal noise ( 10 ), as long as sizable fluctuations exist to activate events, glassy relaxation appears to be universal ( 11 , 12 ).…”