Eur. Phys. J. E (2013) 36: 127
https://doi.org/10.1140/epje/i2013-13127-7

Regular Article

Mesoscale structures from magnetocapillary self-assembly

¹ GRASP, Physics Department B5a, University of Liège, B-4000, Liège, Belgium
² Department of Physics, Graduate School of Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, 112-8610, Tokyo, Japan

^* e-mail: nvandewalle@ulg.ac.be

Received: 9 June 2013
Revised: 19 September 2013
Accepted: 14 October 2013
Published online: 31 October 2013

Abstract

When identical soft ferromagnetic particles are suspended at some water-air interface, capillary attraction is balanced by magnetic repulsion induced by a vertical magnetic field. By adjusting the magnetic field strength, the equilibrium interdistance between particles can be tuned. The aim of this paper is to study the ordering of particles for large assemblies. We have found an upper size limit above which the assembly collapses due to capillary effects. Before reaching this critical number of particles, defects are always present and limit the perfect ordering expected for that system. This is due to the curvature of the interface induced by the weight of the self-assembly.