Electronic structure of Co_1-xFe_xS₂

We present a detailed DFT-based electronic structure calculation of Co _1-xFe_xS₂, a model ferromagnetic system with tunable spin polarization, P. It is shown that the position of the Fermi level and the spin polarization can be controlled by x, the Fe concentration. We predict that for x = 0 the system has predominantly minority carriers corresponding to P = -75%. Upon doping to x = 0.25, the system becomes half-metallic with majority carriers, i.e., P = 100%. The high spin polarization in a wide range of x has been essentially confirmed experimentally.