Magneto-optic measurement of Brownian relaxation of magnetic nanoparticles

Seok Hwan Chung, Marcos Grimsditch, Axel Hoffmann, Samuel D. Bader, Jin Xie, Sheng Peng, Shouheng Sun

Research output: Contribution to journalArticlepeer-review


We demonstrate a magneto-optic technique to measure Brownian relaxation of magnetic nanoparticles suspended in liquids. We used AC susceptibility data as a function of frequency of the applied AC magnetic field to verify that the results agree with those obtained via a conventional inductive detection technique. However, compared with a commercial AC susceptometer using the conventional detection scheme, our magneto-optic setup is able to detect a density of nanoparticles at least three orders smaller. This technique has the potential of being used as a sensor for magnetic nanoparticles such as in local temperature, viscoelasticity, or molecular-binding measurements.

Original languageEnglish (US)
Pages (from-to)91-95
Number of pages5
JournalJournal of Magnetism and Magnetic Materials
Issue number3-4
StatePublished - Feb 2008
Externally publishedYes


  • AC susceptibility
  • Biosensing
  • Brownian relaxation
  • Magnetic nanoparticle
  • Magneto-optic

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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