Clustering transitions in vibro-fluidized magnetized granular materials

TL;DR

This paper investigates how long-range magnetic interactions influence phase transitions and clustering behavior in vibro-fluidized granular materials, revealing phenomena like cluster formation, nucleation, and chain self-assembly.

Contribution

It provides new insights into the phase behavior of magnetized granular materials under vibration, highlighting the effects of magnetic interactions on clustering and self-assembly.

Findings

Clusters form below a certain temperature with growth consistent with nucleation.

Particles in clusters have lower temperature than surrounding gas, indicating non-equipartition.

Magnetic interactions lead to chain self-assembly at low temperatures.

Abstract

We study the effects of long range interactions on the phases observed in cohesive granular materials. At high vibration amplitudes, a gas of magnetized particles is observed with velocity distributions similar to non-magnetized particles. Below a transition temperature compact clusters are observed to form and coexist with single particles. The cluster growth rate is consistent with a classical nucleation process. However, the temperature of the particles in the clusters is significantly lower than the surrounding gas, indicating a breakdown of equipartition. If the system is quenched to low temperatures, a meta-stable network of connected chains self-assemble due to the anisotropic nature of magnetic interactions between particles.