THE ELECTRONIC-STRUCTURE OF MAGNETIC TRANSITION METALLIC MATERIALS

The spin-polarized electronic structure of magnetic transition metallic materials is shown to be a fundamental part of spin density functional (SDF) theory which is able to give a quantitative account of many ground-state magnetic properties. Recent developments in the implementation of this theory are mentioned and comments made concerning the comparison of the electronic structure with spectroscopic measurements. The consequences of spinorbit coupling effects on the electronic structure for magnetic anisotropy are uncovered via a relativistic generalization. The electronic structure of crystalline, magnetic and transition metal alloys is discussed in some detail and the implications for low-temperature, magnetic and related properties given. These include magneto-volume effects and the connection between magnetism and compositional order. Recent work on amorphous, metallic magnets, magnetic overlayers, thin films and multilayers is briefly described. The theory for low-temperature magnetic excitations is outlined in terms of the dynamic, spin susceptibility, which is also based on the electronic structure. This gives an account of spin waves in ferromagnets and spin fluctuations in paramagnets. The picture of the paramagnetic state of transition metal ferromagnets at high temperatures is described in which spin fluctuations are. modelled as 'local moments'. SDF theory is consequently extended to finite temperatures. The underlying electronic structure is shown to be modified in some cases by these collective electronic effects. Throughout the article, the successes and limitations of the theoretical results, when compared to experimental measurements, are set out