Nuclear magnetic resonance investigations of the structure and magnetic properties of metallic multilayers and nanocomposites

As a probe of the short-range chemical and topological order, nuclear magne tic resonance (NMR) has proved useful to investigate the nanostructure of m agnetic multilayers or granular systems and, in particular, to evaluate the nature, sharp or diffuse. of interfaces in such nanocomposites. These stru ctural aspects are shortly reviewed in the paper. A larger emphasis is give n to the magnetic properties that are accessed by the technique. As a first output of an NMR experiment in ferromagnets, the hyperfine field gives a d irect insight on the local magnetization. Hence, for example, one can estim ate the magnetization profile at a diffuse interface between a magnetic and nonmagnetic phase. In addition, NMR can probe selectively the magnetic ani sotropy or exchange energy in different parts of a composite sample. Theref ore NMR is a unique tool to investigate the correlation. at a local scale, between the nanostructure and the magnetic properties of a sample. For exam ple, one can evidence the different magnetic hardness of the interface and bulk moments in multilayers, or of the magnetic clusters and alloyed region s in nanogranular alloys. Some relevant results are presented, which have b een obtained in the course of investigations of Go-based multilayers, ultra thin films and granular systems.