Magnetism of the Elements

Abstract

This chapter presents the magnetic properties of the elements in relation to their magnetic structure, with emphasis on those that order magnetically in bulk form – iron, cobalt, nickel, manganese, chromium, most of the rare earths and oxygen. All except oxygen are metals. The importance of spin polarisation at the Fermi level is illustrated by the three room-temperature ferromagnets: iron, cobalt and nickel. Manganese and chromium are atypical antiferromagnets; α-Mn is a multi-sublattice antiferromagnet, β-Mn is a spin liquid, and Cr exhibits an incommensurate spin density wave. A summary of the magnetism of the rare earth elements emphasises the effects of the crystal field, their moments and exchange integrals on their magnetic structures and phase transitions. Some magnetoelastic effects are discussed, and a detailed account of the spin polarisation of the heavy rare earths concludes the section. Finally, more exotic forms of magnetism such as the molecular antiferromagnetism of oxygen and defect-induced magnetism, exhibited by p and d-shell elements, such as carbon and ruthenium, are presented.