Interparticle magnetic interactions and magnetic field dependence of superparamagnetic blocking temperature in ferrihydrite nanoparticle powder systems

Abstract

In this study, nanoparticles of initial synthetic ferrihydrite have been coated with arabinogalactan. The synthesized series of samples with different degrees of coverage of particles has been characterized by X-ray photoelectron spectroscopy, Mössbauer spectroscopy, transmission electron microscopy and magnetometry. The superparamagnetic blocking temperature decreases monotonically with an increase in the degree of coverage of ferrihydrite particles, which is unambiguously related to the different role of the interparticle magnetic interactions in the investigated powder systems. Analysis of the field dependence of the blocking temperature within the random anisotropy model has shown that an increase in the degree of coverage of ferrihydrite particles leads to a decrease in the size of a cluster in which the behaviors of the nanoparticle magnetic moments are correlated. The results obtained have shown the possibility of effective control of the strength of magnetic interparticle interactions in powder ferrihydrite systems by coating nanoparticles with arabinogalactan.