Non-regularized inversion method from light scattering applied to ferrofluid magnetization curves for magnetic size distribution analysis

• Published in: Journal of magnetism and magnetic materials Vol. 353; pp. 110 - 115
• Main Authors: van Rijssel, Jos, Kuipers, Bonny W.M., Erné, Ben H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2014; Elsevier
• Subjects: AGM; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Density; DLS; Exact sciences and technology; Ferrofluids; Inversions; Least squares method; Light scattering; Magnetic liquids; Magnetic properties and materials; Magnetization curves; Mathematical models; Non-negative least squares fitting; Numerical method; Particle size distribution; Physics; SLS; Small particles and nanoscale materials; Studies of specific magnetic materials; VSM; VSM; Numerical method; DLS; SLS; AGM; Non-negative least squares fitting; Ferromagnetic fluid; Particle size; Magnetization; Light scattering; Magnetic particles; Dipole moments; Least square fit
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2013.10.025

A numerical inversion method known from the analysis of light scattering by colloidal dispersions is now applied to magnetization curves of ferrofluids. The distribution of magnetic particle sizes or dipole moments is determined without assuming that the distribution is unimodal or of a particular shape. The inversion method enforces positive number densities via a non-negative least squares procedure. It is tested successfully on experimental and simulated data for ferrofluid samples with known multimodal size distributions. The created computer program MINORIM is made available on the web. •A method from light scattering is applied to analyze ferrofluid magnetization curves.•A magnetic size distribution is obtained without prior assumption of its shape.•The method is tested successfully on ferrofluids with a known size distribution.•The practical limits of the method are explored with simulated data including noise.•This method is implemented in the program MINORIM, freely available online.