Magnetic Disorder at the Nanoscale

This chapter discusses the correlation between the magnetic structure and the magnetic properties in the rich system of spinel ferrite full nanoparticles and in the system of hollow nanoparticles with very high surface-to-volume ratio. Nanoscience became, one of the most important research areas in modern science. The general physical properties and concepts related to nano-sized objectsdiffer greatly from the corresponding bulk materials. Among nanostructured materials, magnetic nanostructures, particularly magnetic nanoparticles, show many interesting phenomena. The simultaneously satisfaction of different magnetic interactions allows to a certain degree of spin disorder, in this case the magnetic material exhibits a non-collinear spin structure. Disorder associated with random interactions and the competition between them might lead to destruction of long-range order and important change in the magnetic properties. In many studies on ferrimagnetic nanoparticles the reduction of the saturation magnetization with the particle size is attributed to spin canting that yields magnetic disorder at the particle surface.