Determination of the statistics of magnetically induced particle chains in concentrated ferrofluids

The paper presents the determination of the magnetic field dependence of the statistics of nanoparticle one dimensional chains in a 9.3% solid volume fraction ferrofluid, using optical dichroism experiments. It was found that, in a 300 kA/m magnetic field, 4v% of the nanoparticles are contained in one dimensional chains with 2 particles/chain on average. For this purpose, an analytical theoretical model for the influence of the magnetically induced nanoparticle chaining on the linear dichroism in ferrofluids was developed. The model is based on the statistical theory for magnetic nanoparticle chaining in ferrofluids developed by Mendelev and Ivanov. The chains statistics was obtained by means of nonlinear regression of the dichroism data with the theoretical model.