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DY: Fachverband Dynamik und Statistische Physik

DY 40: Poster - Quantum Systems/ Stat. Phys./ Diffusive Process

DY 40.25: Poster

Donnerstag, 3. April 2014, 17:00–19:00, P3

The impact of interactions on the rotational ratchet effect in magnetic colloidal suspensions — •Teresa Reinhard and Sabine H. L. Klapp — Institut für Theoretische Physik, TU Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany

The extraction of directed motion from undirected random motion is a well-known problem with many different applications, such as the efficiency of heat engines, biological transport or nano-motors.
To analyze such effects, we consider a system of dipolar colloids with dipole-dipole interactions that are driven out-of-equilibrium by an oscillating magnetic field. Due to microscopic Brownian motion, these systems can exhibit directed rotational motions without an externally applied net torque [1]. This so-called ratchet effect is analysed on basis of the dynamical density functional theory [2].
Specifically, we investigate the impact of the frequency of the external field, as well as the dependence on the distance vector between the particles.
We compare our results with those from a mean-field Fokker-planck approach [3] and from particle-based computer simulations [4].
[1] A. Engel and P. Reimann, Phys. Rev. Let. 91, 060602 (2003).

[2] M. Rex, H. H. Wensink and H. Löwen,
  Phys Rev E 76, 021403 (2007)

[3] V. Becker and A. Engel Phys. Rev. E 75, 031118 (2007).

[4] S. Jäger and S. H. L. Klapp, Phys. Rev. E 86, 061402 (2012).