Aggregation of superparamagnetic colloids in magnetic fields: The quest for the equilibrium state

Jordi S. Andreu, Juan Camacho, Jordi Faraudo

Research output: Contribution to journalArticleResearchpeer-review

55 Citations (Scopus)

Abstract

Previous experimental and simulation studies of superparamagnetic colloids in a strong external field have systematically shown a nonequilibrium aggregation process in which chains of particles steadily grow in the direction of the applied external field with the average length increasing as a power law over time. Here we show, by employing Langevin dynamics simulations, the existence of a different behavior under the effects of an external magnetic field: after a transient period of chain formation, the system attains an equilibrium state. Furthermore, a thermodynamic self-assembly theory supports the simulation results and it also predicts that the average chain length in the equilibrium state depends only on a dimensionless parameter combining the volume fraction of colloids 0 and the magnetic coupling parameter Γ. The conditions under which this new behavior can be observed are discussed here. © 2011 The Royal Society of Chemistry.
Original languageEnglish
Pages (from-to)2336-2339
JournalSoft Matter
Volume7
DOIs
Publication statusPublished - 21 Mar 2011

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