2020 Impact factor 1.890
Soft Matter and Biological Physics


Eur. Phys. J. E 6, 399-407 (2001)

Cluster structure and the first-order phase transition in dipolar systems

Monte Carlo simulation
A.F. Pshenichnikov and V.V. Mekhonoshin

Institute of Continuous Media Mechanics UB RAS, 1, Korolyev str., 614013, Perm, Russia

pshenichnikov@icmm.ru

(Received 27 April 2001 and Received in final form 23 October 2001)

Abstract
The Monte Carlo technique is used to simulate a 3D dipolar hard-sphere system. The spatial and magnetic structure of clusters formed by magnetic dipolar interactions in zero applied field is investigated. It is shown that the many-particle clusters are characterized by a quasi-spherical shape, extremely small magnetic moments, and a fractal dimension close to three. These clusters are regarded as nuclei of a new concentrated isotropic phase. The numerical simulation of the first-order phase transition has been realized which allows us to find the interface between two coexisting phases. It has been found that the dipole-dipole and steric interactions are sufficient to separate the system into two phases with low and high concentrations of particles. The introduction of any additional attraction potential is not required. The phase diagram of dipolar system in zero applied field has been obtained. The simulation results are in qualitative agreement with the predictions of some analytical models.

PACS
75.50.Mm - Magnetic liquids.
64.70.Fx - Liquid-vapor transitions.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001