Memory strength and capacity versus disorder in polycrystals

Determine how the strength of mechanical memory signals and the capacity to store multiple memories in polycrystalline solids depend on the degree of disorder. Specifically, characterize the relationship between disorder in polycrystals (e.g., the prevalence and structure of grain boundaries relative to crystalline domains) and both (i) the amplitude and robustness of memory readouts and (ii) the ability to retain multiple trained deformation amplitudes, in comparison to amorphous solids.

Background

Polycrystalline solids exhibit localized rearrangements under loading, often concentrated at grain boundaries, and experiments indicate that such systems can form memories of cyclic driving. These rearrangements closely resemble those in amorphous solids in size and magnitude, though they are less numerous in polycrystals.

Despite evidence that polycrystals can form mechanical memories, the influence of their degree of disorder on memory behavior is unresolved. Observations suggest that amorphous solids present strong memories near yielding, whereas 2D Lennard-Jones polycrystals can coarsen into monocrystals approaching yielding, hinting that memory capacity might diminish with reduced disorder. A systematic understanding of how memory strength and multi-memory capacity scale with disorder is therefore missing.