Substituting the main group element in cobalt-iron based Heusler alloys:: Co2FeAl1-xSix

This work reports electronic structure calculations for the Heusler compound Co2FeAl1-xSix. Particular emphasis was put on the role of the main group element in this compound. The substitution of Al by Si leads to an increase in the number of valence electrons with increasing Si content and may be seen as electron-doping. Self-consistent electronic structure calculations were performed to investigate the consequences of the electron-doping on the magnetic properties. The series Co2FeAl1-xSix is found to exhibit half-metallic ferromagnetism and the magnetic moment follows the Slater - Pauling rule. It is shown that the electron-doping stabilizes the gap in the minority states for x = 0.5.