Magnetic measurements as a key for the particle size distribution in ferrofluids: experiment, theory, and computer simulations

A. O. Ivanov - S. S. Kantorovich - E. N. Reznikov - C. Holm - A. F. Pshenichnikov - A. V. Lebedev - A. Chremos - P. J. Camp

Department of Mathematical Physics, Urals State University, 51 Lenin Av., Ekaterinburg 620083, Russia} {Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe Universität, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main, Germany} {Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz, Germany} {Institute of Continuous Media Mechanics, 1 Korolyov Str., 614013 Perm, Russia} {School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, United Kingdom

Abstract
In the present paper, we show the way of finding a particle-size distribution from the experimental magnetization curves for a polydisperse magnetite ferrofluid at various concentrations using the modified mean-field theory of the second order (MMF2). We check the validity of the obtained distribution by computer simulations. To check for consistency, extensive molecular dynamics and Monte Carlo simulations are performed for systems with a discretized version of particle-size distribution p(x) corresponding as closely as possible to that of the real ferrofluid. Essentially perfect agreement between experiment, theory, and computer simulation is demonstrated, thus, proving the MMF2 theory to be an effective tool for the magnetogranulometric analysis for the ferrofluids with a wide range of concentrations. Figs 2, Refs 15.