We report the effect of the substitution of Co with Fe in Co 2-xFexCrGa 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.
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