Unknotting of quasi-two-dimensional ferrogranular networks by in-plane homogeneous magnetic fields

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:499

Article

Sanchez, Pedro A.^1,2  Miller, Justus³  Kantorovich, Sofia S.^1,4  Richter, Reinhard³ 

[1] Ural Fed Univ, 51 Lenin Av, Ekaterinburg 620000, Russia

[2] Helmholtz Zentrum Dresden Rossendorf eV, Inst Ion Beam Phys & Mat Res, D-01314 Dresden, Germany

[3] Univ Bayreuth, Expt Phys 5, D-95440 Bayreuth, Germany

[4] Univ Vienna, Computat Phys, A-1090 Vienna, Austria

关键词: Ferrogranulate mixture;    Transient network;    Viscoelastic phase separation;    Langevin dynamics simulation;    Susceptible dipolar hard spheres;    Field induced network unknotting;   

DOI  :  10.1016/j.jmmm.2019.166182

来源: Elsevier

【 摘 要 】

Our ongoing research addresses, by means of experiments and computer simulations, the aggregation process that takes place in a shaken granular mixture of glass and magnetized ferrous alloy beads when the shaking amplitude is suddenly decreased. After this quenching, the magnetized beads form a transient network that coarsens in time into compact clusters, following a viscoelastic phase separation. Here we focus on the quasi-two-dimensional case, analyzing in computer simulations the effects of a magnetic field parallel to the system plane. Our results evidence that the field drastically changes the structure of the forming network: chains and elongated clusters parallel to the field are favored whereas perpendicular connecting structures tend to be suppressed, leading to the unknotting of the networks which are observed at zero field. Importantly, we found that moderate field strengths lead to the formation of larger clusters at intermediate time intervals than in the case of weak and strong fields. Moreover, the latter tend to limit the overall growth of the clusters at longer time scales. These results may be relevant in different systems governed by similar magnetically driven aggregation processes as, for example, in the formation of iron-rich planetesimals in protoplanetary discs or for magnetic separation systems.

【 授权许可】

Free