Half-metallic character and electronic properties of inverse magnetoresistantFe1−xCoxSialloys

Based on ab initio calculations we find that ${\mathrm{Fe}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$ alloys in the Fe-rich region behave as a disordered ferromagnetic half metal. Half metallicity can explain the recently found electronic, magnetic, and transport properties. We can also determine a sharp transition from the paramagnetic metallic behavior to the ferromagnetic half-metallic state as a function of Co concentration. At concentrations higher than 0.25 the system starts to segregate Co from Fe atoms, this giving rise to the disappearance of half metallicity and to reflect it in the decreasing value of the magnetic moment.