Association Formation in Long-Range Interacting Granular Systems

Granular materials are typically studied as athermal systems where particles interact with each other via short-range contact forces. In experiments, such systems can often be dominated by frictional interactions, causing any local perturbation to be significantly dampened. Inspired by recent work [1], we designed and built disordered 2D granular packings where magnetic particles on a fluid-air interface have long-range interactions. In this nearly frictionless system, we can adjust the length scales of interparticle interactions by modifying the magnetic strength of individual particles. Using this approach, we investigate the presence of memory and the formation of associations in a disordered system under external driving. Our results aim to uncover how such complex structures arise in long-range interacting systems, offering insights into the dynamics of particle associations. Future work will extend this exploration to the impact of local deformations on association formation, giving us new insights in the field of memory formation and physical learning in disordered systems.

[1] Hooshanginejad, A., Barotta, JW., Spradlin, V. et al. Interactions and pattern formation in a macroscopic magnetocapillary SALR system of mermaid cereal. Nat Commun 15, 5466 (2024).