Magnetic Anisotropy in Chemically Synthesized Core-Shell and Composite Nanoparticles

Natalie Frey Huls (NIST)

Chemically synthesized magnetic nanoparticles are currently being studied due to their unique magnetic properties and their potential biomedical applications including biosensing, targeted drug delivery, magnetic field hyperthermia, and magnetic resonance imaging (MRI) contrast enhancement. A promising method for stabilizing the nanoparticle properties - both chemically and magnetically - is to synthesize them with core-shell or composite morphology. This not only leads to additional functionalization but also creates opportunities for studying magnetic interactions at the nanoscale. In this talk I will discuss three chemically synthesized nanoparticle systems, namely FeO-Fe3O4 core-shell nanoparticles, Fe-Fe3O4 core-shell nanoparticles, and Au-Fe3O4 composite nanoparticles, focusing on the magnetic anisotropy that arises due to the interfacial interactions. While the FeO-Fe3O4 nanoparticles show conventional antiferromagnetic-ferrimagnetic exchange bias (which can be tuned by changing the core-shell dimension ratios) the Fe-Fe3O4 and Au-Fe3O4 nanoparticles exhibit magnetic anisotropy behavior more consistent with spin glasslike disorder phase as the origin for the coupling. I'll explain how a variety of measurement techniques, including the transverse susceptibility measurement system in the NIST Magnetic Materials Group, was used to elucidate the similarities and differences in the magnetic behavior of these nanoparticles systems.

Back to Seminar Home Page

Last modified 05-January-2012 by website owner: NCNR (attn: )