The electronic structure, and magnetic and structural properties of Fe - Cu and Fe - Ag alloys

We present the electronic structure, magnetic properties, and structural properties of metastable Fe sub 1-x Cu sub x and Fe sub 1-x Ag sub x alloys over the whole composition range. Although in the equilibrium state (Fe, Cu) and (Fe, Ag) do not form solid solutions, recent experiments show that by using special techniques, continuous and homogeneous solid solutions of (Fe, Cu) and (Fe, Ag) can be formed over the whole concentration range. In the present work, we have used the tight-binding linear-muffin-tin-orbital method with the coherent-potential approximation to calculate the electronic structure and magnetic moment of these alloys. Our calculation of the density of states shows two very clear peaks due to Fe and Cu (Ag), in agreement with the experimental x-ray photoemission spectroscopy results. Also our calculated values of the magnetic moments for different compositions of the alloys are found to be in good agreement with the experimental results. Our calculation shows that an Fe atom in an Fe-Cu alloy has a lower magnetic moment than an Fe atom in an Fe-Ag alloy for the same composition. We have also calculated the heat of formation of these alloys, which we always find to be positive, implying the non-existence of stable phases of these alloys under equilibrium conditions.