The effect of iron addition on the spin polarization and magnetic properties of Co₂CrGa Heusler alloy

We report the effect of the substitution of Co with Fe in Co _2-xFe_xCrGa Heusler alloys (x = 0-0.3) on their magnetic property, electronic band structure and spin polarization, both experimentally and theoretically. The intrinsic spin polarization of Co₂CrGa measured by the point-contact Andreev reflection method was P = 0.61 0.02, whereas a small substitution with Fe for Co of x = 0.1 enhanced the spin polarization to P = 0.67 0.03 regardless of a weak L2₁ order. Ab initio calculations for both the perfectly L2₁ ordered and partially disordered structures showed that the small amount of Fe induced a robustness of the spin polarization against the structural disorder. These results demonstrate the effect of the Fe addition in Co₂CrGa is to improve the spin polarization even with the presence of chemical disorder.