Quantum tunneling of magnetization in nanostructured materials

The study of very low temperature magnetic relaxation in nanostructured materials has provided the opportunity to observe the occurrence of quantum tunneling of magnetization (QTM) in many different systems. As the magnetization is classical vector, this effect is also referred to as macroscopic quantum tunneling (MQT). In this paper, we review the key ideas underlying magnetic relaxation as well as the results obtained for different nanostructured systems, which, to date, include single domain particles, mesoscopic grains, and high-spin polynuclear molecules.