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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 54: Poster Session 3

CPP 54.49: Poster

Donnerstag, 3. April 2014, 15:00–19:00, P2

Effective temperature of an active microrheological tracer in colloidal suspensions — •Robert Wulfert¹, Boris Lander¹, Udo Seifert¹, and Thomas Speck² — ¹II. Institut für Theoretische Physik, Universität Stuttgart, Germany — ²Institut für Physik, Johannes-Gutenberg-Universität Mainz, Germany

It remains an open issue which classes of non-equilibrium systems can be characterized by an effective temperature in a well-defined and meaningful way. A promising and rather generic approach is to consider the fluctuation-dissipation relation (FDR) for driven systems in a non-equilibrium steady state (NESS). We present numerical results obtained via simulation of colloidal suspensions, which are probed by pulling a single tracer particle with a constant force. For this active microrheological scenario, we determine conditions under which the velocity-force FDR becomes approximately time-independent. It can then be interpreted as an effective temperature, accounting for the tracer dynamics on all timescales with a unique value that is equal to the kinetic temperature. Furthermore, we discern in how far the effective temperature depends on the choice of observable by analyzing the anisotropic properties of the tensorial velocity-force FDR.