Berlin 2005 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
DY: Dynamik und Statistische Physik
DY 33: Ferrofluids and Liquid Crystals
DY 33.5: Vortrag
Montag, 7. März 2005, 15:00–15:15, TU H2032
Rosensweig instability and hysteretic behaviour of an inverse ferrofluid — •Christian Gollwitzer1, Reinhard Richter1, Ruben Saldivar-Guerrero2, and Ingo Rehberg1 — 1Experimentalphysik V, Universität Bayreuth, D-95440 Bayreuth — 2Centro de Investigación en Química aplicada, 25100 Saltillo, Coahuila México
An inverse ferrofluid is a suspension of non-magnetic particles in a conventional ferrofluid, and has been first investigated by Skjeltorp1. The particles can be treated as magnetic “holes”, the magnetic moments of which point into the opposite direction of the external magnetic field. The Rosensweig instability of an inverse ferrofluid is investigated and compared to the pattern formation of the base fluid. Due to chain formation and magneto-visco-elastic effects2 the qualitative behaviour changes drastically, in that hysteresis is introduced, which is not present in the base fluid. By the use of X-rays, complete surface profiles can be recorded3 and phase separation of the inverse ferrofluid in gravitational and magnetic gradient fields are observed. In combination with the Rosensweig instability this gives rise to a memory effect.
References:
1A.T. Skjeltorp, Phys. Rev. Lett. 1983
51, 2306
2 R. Saldivar:
Magneto-rheological study of inverse ferrofluids with polystyrene particles of
different size, to be submitted
3R. Richter, J. Bläsing: Measuring surface deformations in
magnetic fluids by radioscopy. Rev. Sci. Instrum. 72,
1729-1733