The Magnetic Properties of Disordered Transition Metal Alloys Using the Coherent Potential Approximation and Related Methods

For many years the properties of magnetic transition metal alloys were analyzed in terms of a rigid band model and the Stoner theory for magnetism in itinerant systems. Recently the introduction of the coherent potential approximation (CPA) has resulted in a description of the band structure of metallic alloys in terms of a local electronic charge density of states. The CPA and related approximations are derived in detail in this article and it is shown how these approximations have been extended to describe the properties of magnetic transition metal alloys in terms of local electronic spin densities. Both the statics and dynamics of itinerant magnetic alloys are discussed and the comparison with experiment is examined in detail. The article is concluded with a description of possible improvements to the CPA for magnetic alloys in particular for local environment effects.