Quasi-elastic neutron scattering on γ-Fe₂O₃ nanoparticles

¹ Laboratoire des Milieux Désordonnés et Hétérogènes (Associated to the CNRS.) , Université Pierre et Marie Curie, Tour 13, Case 78, 4 place Jussieu, 75252 Paris Cedex 05, France
² Laboratoire de Physicochimie Inorganique, Université Pierre et Marie Curie, Bât. F, case 63, 4 place Jussieu, 75252 Paris Cedex 05, France
³ Laboratoire Léon Brillouin, CEN, Saclay Gif-sur-Yvette, France
⁴ Laboratory of Kinetics of Anisotropic Fluids, Urals Branch of the Russian, Academy of Sciences, Perm, 614061, Russia

Received: 3 February 1997
Accepted: 14 October 1997

Abstract

Magnetodynamics of ferrofluid γ- nanoparticles is studied by Quasi-Elastic Neutron Scattering between 10 K and 250 K in the frequency range 10¹⁰–. We probe independently the precession of the core magnetic moment and surface spins fluctuations observed in a dissipative regime. These fluctuations slow down at low temperature leading to a frozen disorder of the surface layer.