Magnetic Materials: Hysteresis in Soft and Hard Magnets

This lecture discusses the properties and applications of magnetic materials, focusing on the hysteresis behavior of soft and hard magnets. It begins with an overview of relevant magnetic fields, including those found in the human brain and on the Earth's surface. The instructor presents data on coercive fields and Curie temperatures, highlighting the significant differences between soft and hard magnets. The lecture emphasizes the importance of understanding coercivity and its implications for material applications, such as transformers and sensors. The instructor explains the relationship between magnetic fields and material properties, using Ashby's plots to illustrate key concepts. The discussion includes the classification of materials based on their hysteresis curves and the factors influencing their performance. The lecture concludes with a focus on the operational points of hard magnets and the significance of microstructure in determining magnetic behavior. Overall, this lecture provides a comprehensive understanding of magnetic materials and their technological relevance.