ELECTRONIC-STRUCTURES AND MAGNETIC-MOMENTS OF FE3+YSI1-Y AND FE3-XVXSI ALLOYS WITH DO3-DERIVED STRUCTURE

We present ab initio calculations of magnetic moments and local electronic densities of states in binary Fe(3+y)Si(1-y) and ternary Fe(3-x) V(x)Si random alloys with DO3-derived structures. The local-spin-density approximation, the linear muffin-tin orbital method, and the coherent-potential approximation (LMTO-CPA) were used. In Fe(3+y)Si(1-y) the excess (as compared to Fe(3Si)) Fe atoms occupy the Si[D] sites of the Fe3Si host and create a strong d scattering. A realistic-alloy calculation thus requires the application of the CPA. In both types of alloys the moments of Fe atoms occupying the B sites remain essentially unchanged when the concentrations (y in Fe(3+y)Si(1-y), x in Fe(3-x)V(x)Si) are varied. The Fe[A, C] moments vary almost linearly with y and x, in agreement with experimental observations. The sublattice density-of-states functions provide insight into the site preference for subtitutional transition-metal impurities in Fe3Si.