Spin polarization of disordered Fe-Cr and Fe-Mn alloys

We present the results of ab initio calculations of the spin-polarized electronic structure of disordered bcc Cr1-xFex and Mn1-xFex alloys. The self-consistent calculations were performed with the coherent potential approximation within the Korringa-Kohn-Rostoker (KKR-CPA) method, using the local-spin-density approximation to treat exchange and correlation. In particular we have calculated the magnetic moments on the Fe and Cr(Mn) sites and the saturation magnetization of alloys. The moments coupling is a function of the alloy concentration and for iron-rich alloys this coupling changes from parallel (ferromagnetic) to antiparallel (antiferromagnetic). In our calculations both alloys have almost linear dependence of saturation magnetization as a function of concentration in a good agreement with the so-called Slater-Pauling curve. The deviations from this linear function in the bcc Mn1-xFex alloy (stable phase at low concentration of Mn and epitaxial phase at high concentrations) are explained by the presence of two-phase regions due to first-order transitions into nonferromagnetic phases.