Magnets have fascinated humans for several thousand years and enabled the age of digital data storage. They occur in various flavors. Ferrimagnets form the largest class of magnets and consist of two types of atoms. Similar to a compass needle, each atom exhibits a little magnetic moment, also called spin, which arises from the rotation of the atom’s electrons about their own axes. In a ferrimagnet, the magnetic moments point in opposite directions for the two types of atoms (see panel A). Thus, the total magnetization is the sum of all magnetic moments of type 1 (M1), blue arrows) and type 2 (M2), green arrows). Due to the opposite direction, the magnitude of the total magnetization is M1-M2.
What happens when we heat the atomic lattice of a magnet all of a sudden?