Diamagnetism

Abstract

Diamagnetism is a property displayed by all materials and is explained semiclassically as an induction effect (χ < 0). With the help of Bohr–van Leeuwen theorem, it is possible, however, to prove that magnetism in any form, that means, including diamagnetism, is a pure quantum mechanical phenomenon. There are qualitative differences between the diamagnetism of insulators and metals. The so-called Larmor diamagnetism of the insulators is a result of the reaction of a completely filled electronic shell to an external magnetic field. The Landau diamagnetism of the conduction electrons of a metallic solid is conceptually more difficult. Its susceptibility consists of three parts, the first one being a diamagnetic component (χLandau < 0) which is ascribed to the orbital motion of the electrons, the second one is a paramagnetic component (χPauli = 0) which is a result of the coupling of the field to the spin of the electron and the third is an oscillatory component which changes sign periodically as a function of the field. The last one leads to the de Haas–van Alphen effect.