Effects of the dipolar interaction on the equilibrium morphologies of a single supramolecular magnetic filament in bulk.

We study the equilibrium morphologies of a single supramolecular magnetic filament in a three-dimensional system as a function of the effective strength of the magnetic dipolar interactions. The study is performed by means of Langevin dynamics simulations with a bead-spring chain model of freely rotating dipoles. We demonstrate the existence of three structural regimes as the value of the dipolar coupling parameter is increased: a coil compaction regime, a coil expansion regime, and a closed chain regime in which the structures tend progressively to an ideal ring configuration. We discuss the governing effects of each regime, the structural transition between open and closed morphologies, and the reasons why we see no multiloop configurations that have been observed in two-dimensional systems under similar conditions.