2021 年 87 巻 902 号 p. 21-00175
In the present study, we have addressed a suspension composed of magnetic cubic particles in a rotating magnetic field by means of quasi-two-dimensional Brownian dynamics simulations in order to investigate the dependence of the regime change on a variety of factors such as the magnetic particle-particle interaction strength, the magnetic particle-field interaction strength and the frequency of the rotating magnetic field. If the magnetic particle-particle interaction strength is relatively small, single particles remain without aggregating to form specific clusters, and the magnetic moments of single particles tend to rotate with the rotating magnetic field. If the magnetic particle-particle interaction strength is predominant, the particles aggregate to form closely-packed face-to-face structures, and the magnetic moments of constituent particles cannot follow a change in the rotating magnetic field. As the magnetic field strength is increased, closely-packed structures start to be transformed into aggregate structures with an offset face-to-face configuration. An increase in the frequency of the rotating magnetic field induces a significant regime change in the aggregate structures. Under the rotating magnetic field with low frequency, the particles aggregate to form elongated clusters with an offset face-to-face configuration along the magnetic field direction, and the cluster itself rotates to follow the change in a rotating magnetic field. From these results, we conclude that a regime change in the aggregate structure of cubic particle in a rotating magnetic field may be induced by various factors such as the magnetic particle-particle interaction strength, the magnetic particle-field interaction strength, and the frequency of the magnetic field.
