SKM 2023 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 7: Granular Matter and Contact Dynamics
DY 7.2: Vortrag
Montag, 27. März 2023, 10:15–10:30, ZEU 148
How is the growth of ferromagnetic granular networks controlled by an orthogonal magnetic field? — Matthias Biersack1, •Ali Lakkis1, Oksana Bilous2, Pedro A. Sanchez2, Sofia S. Kantorovich2, and Reinhard Richter1 — 1University of Bayreuth, Experimental Physics V, 95447 Bayreuth, Germany — 2Computational and Soft Matter Physics, Faculty of Physics, University of Vienna, 1090 Vienna, Austria
We are exploring in experiments the aggregation process in a shaken granular mixture of glass and magnetized steel beads, occuring in a horizontal vessel after the shaking amplitude is suddenly decreased. Then the magnetized beads form a transient network that coarsens in time into compact clusters, following a viscoelastic phase separation [1]. A homogeneous magnetic field oriented in plane has been observed to "unknot" network structures orthogonal to the field [2]. Here we focus on the impact of a magnetic field Bz oriented orthogonally to the plain of the network. We measure the average number of neighbours k(t) and the efficiency E(t) of the emerging networks. Both can be fitted by a logistic growth function for Bz ∈ [0,2] mT, unveiling that its characteristic time τ increases by about ten. Our results demonstrate that via dipole-dipole repulsion the field reduces the mobility of isolated steel beads, thus hindering the growth of the networks. The experimental results are compared with those of numerical simulations.
[1] A. Kögel, et al. Soft Matter, 14 (2018) 1001.
[2] P. A. Sánchez, J. Miller, S. S. Kantorovich, R. Richter, J. Magn. Magn. Mater, 499 (2019) 166182.