Percolation, relaxation halt, and retarded van der Waals interaction in dilute systems of iron nanoparticles

Ralph Chamberlin, J. Hemberger, A. Loidl, K. D. Humfeld, D. Farrell, S. Yamamuro, Y. Ijiri, S. A. Majetich

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

We find three unanticipated features in the magnetic response of dilute systems of highly monodisperse Fe nanoparticles. Above a spin freezing temperature (formula presented) the remanent magnetization relaxes smoothly to zero, but below (formula presented) the relaxation halts abruptly at a nonzero value. The distribution of relaxation rates changes at a percolation temperature (formula presented) consistent with chainlike structures above (formula presented) and three-dimensional clusters below (formula presented) The blocking temperature (formula presented) varies inversely proportional to particle diameter, opposite to the behavior of the Néel-Brown model for individual domains, but consistent with a type of Casimir-Polder interaction expected between dilute nanometer-scale particles.

Original languageEnglish (US)
Pages (from-to)1-4
Number of pages4
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume66
Issue number17
DOIs
StatePublished - Jan 1 2002

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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