Magnetic Materials: Hysteresis Curves Explained

This lecture focuses on the hysteretic behavior of magnetization in magnetic materials, particularly soft and hard magnets. The instructor begins by reviewing the exchange interaction and its significance in magnetic ordering, emphasizing that the exchange interaction is a strong force that leads to high ordering temperatures. The discussion then transitions to hysteresis curves, which illustrate how magnetization varies with an external magnetic field. The instructor explains the importance of understanding these curves, including the distinction between extrinsic and intrinsic properties of materials. Key terms such as saturation magnetization, remanent magnetization, and coercive field are defined and illustrated through examples. The lecture also covers the implications of hysteresis in practical applications, such as transformers and magnetic storage devices. The instructor encourages student participation by asking them to sketch hysteresis curves and discuss their characteristics. Overall, the lecture provides a comprehensive overview of the principles governing magnetic materials and their applications in technology.