Magnetism and Magnetic Materials

This chapter explains the journey of modern magnetism from the beginning of the twentieth century, a remarkable age of scientific breakthroughs that led tithe birth of quantum mechanics and special relativity. A modern understanding of magnetism is based on the concept of spin, which is a purely quantum mechanical property with no classical analogy. To discuss magnetism in a contemporary perspective, therefore, we should start from quantum mechanics. Rather than simply going through formula derivations and jumping into the modern‐yet‐hindsight spin‐based interpretation of microscopic origin of magnetism in matters, instead, the chapter briefly discusses the history of its development. Depending on their responses to the applied magnetic field, these magnetic properties can be roughly categorized into diamagnetism, paramagnet‐ism, ferromagnetism, anti ferromagnetism, and ferrimagnetism. Diamagnetism is present in all materials but is often obscured by paramagnetism or ferromagnetism when unpaired electrons are in presence.