Nanoparticles are widely studied systems for a variety of applications; however, as the surface plays the major role in deciding the overall properties, characterization of the surface becomes as important as the characterization of the structure itself. The underlying physics regarding exchange interactions and bonding can be elucidated by studying the structure of the surface and core. Doping allows us to change the overall spin arrangement, and investigate the competition between ferro- and antiferromagnetic interactions.

To undertake a rigorous characterization of exchange interactions at the surface and in the core of nanoparticles, I utilize different shapes of Co3O4 and dopings of CuxCo3-xO4 nanoparticles. The antiferromagnetic arrangement of Co3O4 is ideal for studying changes in the magnetism. Due to the competition of ferro- and antiferromagnetic interactions small changes in the exchange can result in large changes in the magnetism.

By studying the shapes in the context of the exposed surface planes, differences in the structure of the surface terminations can be correlated to the exchange interactions leading to quantification of the surface exchange and magnetism. On the other hand, by doping Cu into the structure of Co3O4 we can examine the affects that modify the exchange interactions in the core of the particle. The role of Cu becomes extremely important to the exchange interactions creating ligand holes between magnetic ions, facilitating ferromagnetic exchange between the ions. The different shapes, and Cu-doping, allow us to explore the relations between the exchange interactions and the overall magnetism in nanoparticles, where the surface is shown to be directly responsible for differences to the bulk magnetism.