Magnetic nanoparticles

Intrinsic properties of magnetic nanoparticles are reviewed, with special e mphasis on the effects of finite size on zero-temperature spin ordering, ma gnetic excitations, and relaxation. Effects on zero-temperature spin orderi ng include moment enhancement due to band narrowing in 3d transition metal particles, surface spin disorder in ferrite particles, and multi-sublattice states in antiferromagnetic oxide particles. Magnetic excitations include discretized spin wave modes, and surface modes that have been detected by q uasielastic neutron scattering. Thermally activated and quantum tunneling r elaxation is discussed in the context of ideal single-domain particles, as well as particles with surface spin disorder. (C) 1999 Elsevier Science B.V . All rights reserved.