ABSTRACT
This chapter helps the reader to learn the basics of magnetism. It assumes the existence of magnetic moments and provides explanations for the various phenomena displayed by dia-, para-, and ferro- magnetism. The chapter also helps the reader to learn about hysteresis, domain formation, the magnetocaloric effect utilized for refrigeration purposes, mean field theories of paramagnetic-ferromagnetic phase transition, and the Monte Carlo simulation method to study the magnetic phase transition in a ferromagnetic Ising model. The intrinsic spin angular momentum of an electron, the Coulomb electrostatic repulsion, and the Pauli exclusion principle are the key ingredients to unraveling the origins of magnetism. The chapter focuses on the demagnetizing field energy, the Zeeman energy term, magnetocrystalline anisotropy energy, and magnetostriction term. The Bohr-van Leeuwen theorem, based on classical statistical mechanics, states that at any finite temperature and in all finite electric and magnetic fields, the net magnetization of a collection of electrons in thermal equilibrium vanishes identically.
