Calculated magnetic properties of binary alloys between Fe, Co, Ni, and Cu

We present a detailed theoretical investigation of the magnetic properties of all the binary alloys between the $3d$ elements Fe, Co, Ni, and Cu, in the fcc, bcc, and hcp structures using the coherent-potential approximation in combination with a linear muffin-tin orbitals basis set. We consider random, ordered, and partially ordered alloys. Theory is shown to successfully reproduce the magnetic properties of these alloys, and allows an understanding of the physics of the formation of magnetic moments in these systems. We have investigated the correlation between magnetism and local chemical and magnetical surrounding, and find that Fe and Ni display rather different behavior. Our study shows that there is an alloy-induced high-spin–low-spin magnetic phase transition in all Fe-based fcc and hcp alloys. The limitations of a collinear spin model and the Weiss model for explaining the Invar effect are discussed on basis of noncollinear calculations for fcc Fe.