Positional ordering induced by dynamic steric interactions in superparamagnetic rods

Chase Austyn Brisbois, Monica Olvera de la Cruz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The dynamic motion produced by precessing magnetic fields can drive matter into far-from-equilibrium states. We predict 1D periodic ordering in systems of precessing rods when magnetic interactions between rods remain insignificant. The precession angle of the rods is completely determined by the field's precession angle and the ratio of the field's precession frequency and the characteristic response frequency of the rods. We develop a molecular dynamics model that explicitly calculates magnetic interactions between particles, and we also simulate rods in the limit of a strong and fast precessing magnetic field where inter-rod magnetic interactions are negligible, using a purely steric model. Our simulations show how steric interactions drive the rods from a positionally disordered phase (nematic) to a layered (smectic) phase. As the rod precession angle increases, the nematic-smectic transition density significantly decreases. The minimization of unfavorable steric interactions also induces phase separation in binary mixtures of rods of different lengths. This effect is general to any force that produces precession in elongated particles. This work will advance the understanding and control of out-of-equilibrium soft matter systems.

Original languageEnglish (US)
Pages (from-to)851-857
Number of pages7
JournalSoft Matter
Issue number5
StatePublished - Jan 12 2023

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics


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