Temperature-Induced Magnetization
DOI: 10.1063/1.2408574
Of anti-ferromagnetic (AF) nanoparticles has now been explained. Because neighboring magnetic moments are antiparallel, a typical AF material has no net magnetization. And any magnetization should decrease as the thermal fluctuations of its spins increase with rising temperature. Yet experiments have shown that both of these behaviors can be violated in AF particles that are just a few nanometers across. Often, an AF material is modeled as two sublattices of oppositely directed magnetic moments. Two physicists at the Technical University of Denmark have now determined that the sublattices in AF nanoparticles precess in such a way that the moments are not strictly antiparallel to each other, which leads to a net magnetization that increases with temperature. The thermally induced magnetization is inversely proportional to volume and thus is apparent in nanoparticles but not in bulk material. The researchers say that the effect will be encountered more frequently as the field of nanotechnology continues to expand. (
