球状磁性ヤヌス粒子からなる分散系を対象にした擬2次元モンテカルロ・シミュレーション（磁気モーメントが粒子中心から横方向にずれた粒子モデル）

Abstract

I have addressed a magnetic Janus particle suspension in the thermodynamic equilibrium situation. The magnetic moment of Janus particles treated in the present study is shifted from the particle center, which is perpendicular to the magnetic moment direction. From the viewpoint of elucidating the internal structure of particle aggregates in a three-dimensional (3D) system, I have treated a dispersion composed of magnetic Janus particles with a full 3D rotational ability in a quasi-two-dimensional (2D) system. The quasi-2D Monte Carlo simulations have been performed in order to investigate the dependence of a regime change in the aggregate structures on various factors such as the magnetic particle-particle interaction strength, magnetic particle-field interaction strength and the distance of the magnetic moment from the particle center. In no applied magnetic field, the Janus particles aggregate to form a stable cluster unit composed of 2-4 particles if the magnetic particle-particle interaction strength is increased. As the magnetic field is increased, the cluster units collapse and chain-like clusters are formed aligned in the magnetic field direction. In the situation of a strong magnetic field, the chain-like clusters composed of Janus particles tend to be thicker as the magnetic moment is shifted away from the particle center. This is because the magnetic interaction between neighboring particles increases due to the magnetic moments of constituent particles in chain-like clusters being closer to each other. The present results are useful for elucidating the internal structure of complex aggregates in a 3D system.