THE ELECTRONIC-STRUCTURE OF MAGNETIC TRANSITION METALLIC MATERIALS

The spin-polarized electronic structure of magnetic transition metalli c materials is shown to be a fundamental part of spin density function al (SDF) theory which is able to give a quantitative account of many g round-state magnetic properties. Recent developments in the implementa tion of this theory are mentioned and comments made concerning the com parison of the electronic structure with spectroscopic measurements. T he consequences of spinorbit coupling effects on the electronic struct ure for magnetic anisotropy are uncovered via a relativistic generaliz ation. The electronic structure of crystalline, magnetic and transitio n metal alloys is discussed in some detail and the implications for lo w-temperature, magnetic and related properties given. These include ma gneto-volume effects and the connection between magnetism and composit ional order. Recent work on amorphous, metallic magnets, magnetic over layers, thin films and multilayers is briefly described. The theory fo r low-temperature magnetic excitations is outlined in terms of the dyn amic, spin susceptibility, which is also based on the electronic struc ture. This gives an account of spin waves in ferromagnets and spin flu ctuations in paramagnets. The picture of the paramagnetic state of tra nsition metal ferromagnets at high temperatures is described in which spin fluctuations are. modelled as 'local moments'. SDF theory is cons equently extended to finite temperatures. The underlying electronic st ructure is shown to be modified in some cases by these collective elec tronic effects. Throughout the article, the successes and limitations of the theoretical results, when compared to experimental measurements , are set out.