Two-dimensional Monte Carlo simulations of a colloidal dispersion composed of rod-like ferromagnetic particles in an applied magnetic field

We investigated the influence of an external magnetic field on microstructures in a colloidal dispersion composed of rod-like ferromagnetic particles using the cluster-moving Monte Carlo method. The internal microstructures obtained by simulations have been analysed in terms of the orientational distribution and pair correlation functions. The results obtained are summarized as follows. As the magnetic field increases, the particles align in the direction of the magnetic field. In the case of a relatively strong magnetic interaction between particles, chain-like clusters are formed along the magnetic field direction. However, the aspect ratio of the particles and the magnetic interaction between them do not affect their orientational distribution. Two types of structures are observed in the chain-like clusters - a straight linear structure and a step-like structure. The chain-like clusters become shorter when the area fraction of the particles decreases, and the number of step-like structures increases when the area fraction of the particles increases. The step-like structure formation can be explained by the dependence of the potential energy curves on the shape of the spherocylinder particles.