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Updated: May 1, 2026

Using Magnetometry to Monitor Cellular Incorporation and Subsequent Biodegradation of Chemically Synthetized Iron Oxide Nanoparticles
Published on: February 27, 2021
Direct observation of magnetic metastability in individual iron nanoparticles
Ana Balan1, Peter M Derlet2, Arantxa Fraile Rodríguez3
1Swiss Light Source, Paul Scherrer Institut, Villigen PSI 5232, Switzerland.
Abstract:
X-ray photoemission electron microscopy combined with x-ray magnetic circular dichroism is used to study the magnetic properties of individual iron nanoparticles with sizes ranging from 20 down to 8 nm. While the magnetocrystalline anisotropy of bulk iron suggests superparamagnetic behavior in this size range, ferromagnetically blocked particles are also found at all sizes. Spontaneous transitions from the blocked state to the superparamagnetic state are observed in single particles and suggest that the enhanced magnetic energy barriers in the ferromagnetic particles are due to metastable, structurally excited states with unexpected life times.
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