Anisotropy and Hard Magnets

This lecture covers the fundamental concepts of anisotropy and hard magnets, including the exchange interaction, hysteretic behavior of magnetization, anisotropy, applications of hard magnets, magnetic domains, and domain walls. It also discusses the development of permanent magnets, key figure of merit (BH)max, and the characteristics of hard-magnetic materials. The lecture emphasizes the importance of energy product, coercive field, and uniaxial anisotropy in hard magnets, highlighting the role of rare earth elements with large spin-orbit coupling. Various structural qualities and features of hard magnets are explored, along with the challenges related to the supply chain of rare earth elements.