Regensburg 2004 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 11: Ferrofluids

DY 11.3: Vortrag

Montag, 8. März 2004, 11:00–11:15, H3

The Hysteresis of the Normal Field Instability — •Reinhard Richter — Experimentalphysik 5, Univ. Bayreuth, 95440 Bayreuth

Ferrofluids or magnetic liquids are colloidal suspensions of magnetic nanoparticles. Their behaviour can be controlled by external magnetic fields. E.g. a horizontally extended layer of magnetic liquid, subjected to a normally oriented magnetic field forms liquid spikes when a threshold of the field amplitude is surpassed. This normal field or Rosensweig instability can be described by a sub critical bifurcation.

We analyse the profile of the liquid spikes and their field dependence by means of contact radiography near the onset and in the hysteretic regime, in order to pave the way for a more precise description by amplitude equations.