Berlin 2008 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 6: Ferrofluids
DY 6.3: Vortrag
Montag, 25. Februar 2008, 15:00–15:15, A 053
Reorientation of a Ferrofluidic Torsional Pendulum Observed in an Oscillating Magnetic Field — •Harald Brendel1, Reinhard Richter1, Ingo Rehberg1, and Mark Shliomis2 — 1Experimentalphysik V, Universität Bayreuth, D-95444 Bayreuth — 2Ben Gurion University of the Negev, Beer Sheva, Israel
Recently a new type of torsional pendulum was proposed [1] which we realize by suspending a disc shaped container in a Helmholtz pair of coils driven by an alternating sinusoidal current. The container is suspended with its long axis in line with the fiber. In contrast to a spherical pendulum [2,3] the orientation of the disc is sensitive both to the field direction and the field frequency: It should expose its edge to the field vector of low oscillating field and its broad side to the field vector of high frequency.
Unfortunately, this reorientation (FLIP) can hardly be realized for available ferrofluids because of their polydispersity. But with help of an additional constant magnetic field, which is orientated perpendicular to the oscillating one, the FLIP of the pendulum can be observed.
In this case one is able to tune the FLIP frequency by varying the amplitude of the help field. This effect is a
physical mechanism in principal, which should occur in electrical polarized matter, too.
[1] M.I. Shliomis, M.A. Zaks, Phys. Rev. E, 73, 066208 (2006).
[2] A. Engel, H.W. Müller, P. Reimann, and A. Jung,
Phys. Rev. Lett. 91, 060602 (2003).
[3] M.I. Shliomis, M.A. Zaks, Phys. Rev. Lett., 93, 047202 (2004).