Magnetic Nanoparticles: Different Systems for a Patchwork of New Effects in Magnetism

Many of the important problems of layers and multilayers, such as the nature of the interfaces (chemical gradient. . . ), their topology (roughtness lenghscale. . . ), . . . and their effects on physical properties (modulus and direction of the interfacial magnetization, interfacial anisotropics, coupling through non magnetic layers, polarized conduction. . . ) are also of prime importance in small magnetic particles. Several types of small particles can be produced using different techniques e. g. size-distributed and randomly dispersed particles (metallurgy. . . ) or artificial 2-D lattices (lithography. . . ). The main difference with layers and multilayer obviously comes from the fact that, in these lattices, the “nano-periodicity” is not limited to one dimension. This pushes the layers and multilayers systems towards a new field of “well controlled complex systems”.