Internal Magnetic Structure of Nanoparticles Dominates Time-Dependent Relaxation Processes in a Magnetic Field

Cindi L. Dennis, Kathryn L. Krycka, Julie A. Borchers, Ryan D. Desautels, Johan Van Lierop, Natalie F. Huls, Andrew J. Jackson, Cordula Gruettner, Robert Ivkov

Research output: Contribution to journalArticlepeer-review


Magnetic nanoparticles provide a unique combination of small size and responsiveness to magnetic fields making them attractive for applications in electronics, biology, and medicine. When exposed to alternating magnetic fields, magnetic nanoparticles can generate heat through loss power mechanisms that continue to challenge a complete physical description. The influence of internal nanoparticle (intracore) magnetic domain structure on relaxation remains unexplored. Within the context of potential biomedical applications, this study focuses on the dramatic differences observed among the specific loss power of three magnetic iron oxide nanoparticle constructs having comparable size and chemical composition. Analysis of polarization analyzed small angle neutron scattering data reveals unexpected and complex coupling among magnetic domains within the nanoparticle cores that influences their interactions with external magnetic fields. These results challenge the prevailing concepts in hyperthermia which limit consideration to size and shape of magnetic single domain nanoparticles.

Original languageEnglish (US)
Pages (from-to)4300-4311
Number of pages12
JournalAdvanced Functional Materials
Issue number27
StatePublished - Jul 2015


  • alternating magnetic fields
  • hyperthermia
  • hysteresis
  • magnetic nanoparticles
  • micromagnetic structures
  • multidomain

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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