ESR line shape of paramagnetic particles in a magnetic liquid. Theory and experiment

A basic model has been proposed to describe the resonance spectra of the paramagnetic sensor particles in dispersions of magnetic nanoparticles aggregated in chains. A theory of the line shape of low-mobility sensors has been developed in the case of chains of a sufficiently homogeneous length. A specific line shift has been shown to appear in such systems and the spectrum may be asymmetric. The ESR spectra of a magnetite-based magnetic liquid have been measured and the main parameters of the chains have been determined.