A ferrofluid based on magnetic nanoparticles of CoFe2O4 molecules dispersed in H2O with the nanoparticle concentration of 3% is studied using the μSR method. The structure and magnetization of the ferrofluid depends on its viscosity. At room temperature (290 K) and the external magnetic field of 527 Gs the observed additional magnetization is ~20 Gs. 


A small fraction of the sample (~20%) shows negative magnetization (diamagnetism). At a low temperature (~30 K) the sample in the magnetic field behaves like a paramagnet. The magnetic field inside and in the near vicinity of the CoFe2O4 nanoparticle is found to be 1.96 ± 0.44 kGs.

The authors:

M. Balasoiu 2,3, D. Buzatu 4, S. I. Vorobiev 1, A. L. Getalov 1, K. I. Gritsai 2,
V. N. Duginov 2, E. N. Komarov 1, S. A. Kotov 1, K. Stan 4, and G. V. Shcherbakov 1

National Research Center “Kurchatov Institute”–Petersburg Nuclear Physics Institute, Gatchina, Leningrad oblast, 188300 Russia
Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia
Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania
Politehnica University, Bucharest, Romania