[COM_RESOURCES_DRAFT_INTERNAL] MCW07 A Mean-Field Model for Magnetism in Gold Nanoparticles
| Category | Online Presentations |
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| Abstract | The onset of magnetism in gold nanoparticles is an intriguing phenomenon with a very rich physics. Macroscopic gold is diamagnetic, but bare gold nanoparticles may exhibit ferromagnetism in a certain size range. In fact, the observed experimental behavior is that the magnetic moment per atom rises from its atomic value to a maximum and then decays to its bulk value.
In this contribution we will present a mean-field semi-classical model that considers a gold nanoparticle as a magnetic core-shell spherical structure with a diamagnetic core and a ferromagnetic surface. In the absence of the diamagnetic core, the spherical average of the surface moments would vanish. Taking into account the presence of the core, leads to an internal magnetic field (similar to the Weiss molecular field) that breaks the spherical symmetry thereby leading to non-vanishing magnetic moments. As the size of the nanoparticle increases, the number of atoms in the core grows faster than the number of surface atoms, leading to a net zero moment. Thus our model correctly explains the observed experimental trend. |
| Cite this work | Researchers should cite this work as follows: |
| Time | 11:30 AM, July 20, 2007 |
| Location | Burton Morgan Building, Purdue University, West Lafayette, IN |
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