What keeps a magnet working? ‘Quantum magnetism’ describes Pierre Curie's work that showed ferromagnets lose their magnetism above a certain critical temperature, now known as the Curie temperature. A full explanation of magnetism came with the development of quantum mechanics in the 1920s by Niels Bohr, among others. Quantum mechanics states that the fundamental description of a quantum object, such as an electron, or a set of electrons, is controlled by a special mathematical function called the wave function. This varies in space, and the magnitude of the square of this function at a particular place gives you the probability that the quantum object is found there.