Analysis of the ferrofluid microstructure based on the static magnetic measurements

In this work, we applied regularized inversion method [New J. Phys. 19, 073012 (2017)] for microstructure analysis of 10 ferrofluid samples with different ferroparticle concentrations, which were obtained by diluting of the first one. The experimental measurements of the magnetization M(H) of all samples were subjected to numerical inversion using 120 ferroparticle fractions. Since volume concentration of ferrofluid samples does not exceed 3%, the properties of each fraction were described using Langevin theory. The magnetogranulomertic analysis confirmed that all 10 samples have the same magnetic moment distribution function, which has two peaks. The first (small) peak in the magnetic moment distribution function demonstrates the presence of a certain number of aggregates or correlated ferroparticle structures in the samples, whose magnetic moments have been compensated. The second peak corresponds to ordinary single particles distributed in the sample. The main advantage of using numerical inversion method is the absence of an a priori fixed form of the distribution function instead of a standard log-normal or Gamma-distribution.