Issue
EPL
Volume 86, Number 1, April 2009
Article Number 10005
Number of page(s) 5
Section General
DOI http://dx.doi.org/10.1209/0295-5075/86/10005
Published online 21 April 2009
EPL, 86 (2009) 10005
DOI: 10.1209/0295-5075/86/10005

Relaxation of the field-induced structural anisotropy in a rotating magnetic fluid

E. Wandersman1, E. Dubois1, F. Cousin2, V. Dupuis1, G. Mériguet1, R. Perzynski1 and A. Cēbers3

1   Laboratoire PECSA, UPMC - CNRS - ESPCI, UMR 7195 - case 51, 4 place Jussieu, 75005 Paris, France, EU
2   Laboratoire Léon Brillouin - CEA-CNRS UMR 12, CEA-Saclay - 91191 Gif-sur-Yvette, France, EU
3   Institute of Physics, University of Latvia - Salaspils-1, LV-2169, Latvia, EU

regine.perzynski@upmc.fr

received 27 January 2009; accepted in final form 12 March 2009; published April 2009
published online 21 April 2009

Abstract
The relaxation of field-induced anisotropy in a magnetic fluid with dominant repulsion is theoretically modeled and experimentally measured by small angle neutron scattering on a sample rotating at angular velocity $\omega $. The scattered pattern distortion scales as the Mason number $Mn=\omega \cdot \tau _{q}$, $\tau _{q}$ being the q-dependent diffusion time of nanoparticles. The model accounts for the magnetophoretical drift in the non-homogeneous self-magnetic field of the assembly, continuously created by the thermal noise. The Mn-dependence of the pattern distortion is well described without any adjustable parameter.

PACS
05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.
83.85.Hf - X-ray and neutron scattering.
82.56.Na - Relaxation.

© EPLA 2009