Relaxation of the field-induced structural anisotropy in a rotating magnetic fluidE. 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
received 27 January 2009; accepted in final form 12 March 2009; published April 2009
published online 21 April 2009
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 . The scattered pattern distortion scales as the Mason number , 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.
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