Magnetism in closed-shell metallic nano-systems
Vladimiro Mujica
Department of Chemistry and Biochemistry, Arizona State University, Phoenix, Arizona, Etats-Unis.
Lundi 23 Juin 2014, 14h00
bibliothèque LCT, tour 12 - 13, 4e étage
The magnetic properties of nano-materials can differ substantially from those of the same substance in bulk. This is particularly true for systems in closed-shell electronic states, which are diamagnetic in bulk, e.g. gold, but exhibit a very rich magnetic behavior in the nano-scale. In addition to this emergent behavior, the optical response of metal nano-particles is strongly influenced by their magnetic properties. For instance, an inverse correlation between plasmon resonance absorption and the onset of magnetization has been observed in gold.
In this talk I will review some of the most striking experimental evidence on nanomagnetism as well as our recent theoretical work on the subject. We consider ab initio electronic structure calculations in metal clusters, as well as spin quantum models to explore the spin symmetry breaking ultimately responsible for the magnetic behavior in closed-shell systems. In addition, we use mean-field statistical models to interpret the size-dependent behavior of the magnetization, which assume that the magnetism in nano-particles is essentially a surface property.