2008/06/20 by J. Černák, Jozef Černák, Geir Helgesen · 22 citations
Biochemistry, Genetics and Molecular Biology · Engineering · Environmental Science · Mathematics · Physics and Astronomy · #Brownian motion #Characterization and Applications of Magnetic Nanoparticles #Cluster (spacecraft) #Cluster size #Condensed matter physics #Diffusion #Geometry #Magnetic and Electromagnetic Effects #Magnetic field #Mathematics #Minerals Flotation and Separation Techniques #Physics #Quantum mechanics #Scaling #Thermodynamics #cond-mat.soft
paper · pdf · doi:10.1103/physreve.78.061401
published in Physical Review E 78(6), 061401 (American Physical Society)
arxiv created 2008/06/20 · openalex publication_date 2008/12/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We experimentally investigated field-induced aggregation of nonmagnetic particles confined in a magnetic fluid layer when rotating magnetic fields were applied. After application of a magnetic field rotating in the plane of the fluid layer, the single particles start to form two-dimensional clusters, like dimers, trimers, and more complex structures. These clusters aggregated again and again to form bigger clusters. During this nonequilibrium process, a broad range of cluster sizes was formed, and the scaling exponents z and z;' of the number of clusters N(t) approximately t;-z;' and average cluster size S(t) approximately t;z were calculated. The process could be characterized as diffusion-limited cluster-cluster aggregation. We found that all sizes of clusters that occurred during an experiment fall on a single curve, as the dynamic scaling theory predicts. However, the characteristic scaling exponents z;',z and crossover exponents Delta were not universal. A particle tracking method was used to find the dependence of the diffusion coefficients Ds on cluster size s . The cluster motions show features of Brownian motion. The average diffusion coefficients Ds depend on the cluster size s as a power law Ds proportional, variants;gamma where values of gamma as different as gamma=-0.62+/-0.19 and gamma=-2.08+/-0.51 were found in two of the experiments.