Effect of Cr substitution for Fe on the spin polarization of $Co2CrxFe1−xSi$ Heusler alloys Available to Purchase

We have investigated the effect of Cr substitution for Fe on the spin polarization, $P$⁠, of $Co2CrxFe1−xSi$ alloys using the point contact Andreev reflection method. A steep increase from $P=0.57$ to $P=0.64$ occurs by a small substitution of Cr for Fe of $x=0.02$⁠, thereafter $P$ values are constant for higher Cr concentrations up to $x=0.4$⁠. The increase in spin polarization can be attributed to both the improved $L21$ ordering found experimentally as well as the half-metallicity predicted by ab initio calculations in the composition range of $0≤x≤0.5$⁠. We propose the composition range of $0.02≤x≤0.1$ is the most promising for ferromagnetic electrodes of magnetic tunneling junctions to achieve high tunneling magnetoresistance.