Nanoscale Magnetism

Alex Punnoose
Department of Physics, Boise State University

Abstract:
Magnetism of nanoscale materials is very fascinating because of their technological applications and because their magnetic properties differ substantially from the bulk counterparts due to the increasing role of the surface spins as the particle size is decreased.  The antiferromagnetic nanoparticle systems below their Néel temperature provide a particularly interesting case since any observed ferromagnetic-like moment must result from uncompensated surface spins and therefore becomes a direct measurement of the properties of the attractive surface atoms/spins. Temperature dependent magnetic effects of the surface spins lead to several very interesting phenomena like superparamagnetism, magnetic hysteresis, exchange bias and interparticle interactions.  I will illustrate these unusual properties of nanoscale magnetic materials using our recent studies on antiferromagnetic CuO nanoparticles.  A detailed understanding of these complex but interesting properties are very essential to study the presence and role of magnetic nanoparticles in several areas of science and technology including spintronics, biomedical research, and catalysis. I will briefly discuss the role of nanoscale magnetism in these different research areas using specific examples, currently investigated by our research group.