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Updated: Apr 22, 2026

Stable Aqueous Suspensions of Manganese Ferrite Clusters with Tunable Nanoscale Dimension and Composition
Published on: February 5, 2022
Field-dependent Brownian relaxation dynamics of a superparamagnetic clustered-particle suspension
1Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan.
Abstract:
The distinguishable Brownian relaxation dynamics of a clustered-particle system of superparamagnetic iron oxide nanoparticle suspension compared to that of a dispersed-particle system has been experimentally investigated through characterization of the frequency and field strength dependences of complex magnetic susceptibility. We confirmed that the application of low sinusoidal magnetic field strength enables cluster rotation instead of individual particle rotations. Furthermore, we found that the cluster rotation was altered to individual particle rotations in higher field strength, resulting in a shorter Brownian relaxation time, which suggests a change in the hydrodynamic volume. This evolutional relaxation behavior was associated with a change in the fitting parameter which satisfies the empirical model of relaxation and further represents the significance of interparticle interactions in defining the nonlinearity of the magnetization response.
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