Influence of nanostructure (layers and particles) on the magnetism of rare-earth materials

Elemental rare-earths R (Gd, Dy, Tb) are prepared in layer and particle form to look at the effects of geometry (layers or particles) and size (layer thickness or particle diameter) on their magnetism. All of the rare-earth systems show a maximum in coercivity (measured at 4.5 K) at about 10 nm (average particle diameter or layer thickness). Magnetic ordering temperature is reduced significantly compared to the bulk when size is reduced below 10 nm for both the layer and the particle geometry. Geometry has a significant effect on the maximum coercivity with particles tending to have larger coercivity than layers.