Dynamics of a flexible ferromagnetic filament in a rotating magnetic field.

Flexible magnetic filaments have garnered considerable attention as prospective materials for the creation of different microdevices. We describe a theoretical model of a ferromagnetic filament and derive its equations of motion by variational techniques. The numerical algorithm used to solve the filament dynamics in magnetic fields of different configurations is described. It is found that in a rotating field the filament transitions between synchronous and asynchronous regimes with respect to the rotating field, similarly to a rigid magnetic dipole. The mean angular velocity of the filament is well described by a relation valid for a rigid magnetic dipole with quantitative differences attributable to the flexibility of the filament.