Regime change in the aggregate structure of magnetic disk-like particles in a quasi-2D suspension system via multi-particle collision dynamics simulations

Abstract

We have addressed the problem of controlling a regime change in a quasi-2D system of magnetic disk-like particles by means of the strength and direction of an applied magnetic field. In the present study, two typical directions have been addressed, i.e. a y-direction field parallel to the 2D plane and a z-direction field normal to that plane of the particle disk. It is shown that the direction of an applied magnetic field is a significant factor in particle aggregation and can give rise to different regime changes. That is, an applied magnetic field parallel to the 2D system plane functions to induce a regime change in the aggregate structure from linear column-like particle clusters into a knitting-pattern formation, whereas in the case of an applied field normal to the 2D plane, a regime of long column-like clusters transforms into a particle distribution with no discernible internal structure. Key points of the present paper: The direction of an applied magnetic field may give rise to significantly different regime changes in particle aggregation. An applied magnetic field parallel to the 2D system plane induces a regime change from long linear column-like clusters into a knitting-pattern formation. A magnetic field in a direction normal to the 2D plane induces a regime change from long linear column-like clusters into a regime with no discernible internal structure. The strength and the direction of an applied magnetic field is a feasible tool for controlling a regime change in the aggregate structure.