Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1-xCrxSi

In this paper, we investigate the half-metallicity of Heusler alloys Fe2Co1-xCrxSi by first principles calculations and anisotropy magnetoresistance measurements. It is found that, with the increase of Cr content x, the Fermi level of Fe2Co1-xCrxSi moves from the top of valence band to the bottom of conduction band, and a large half-metallic band gap of 0.75 eV is obtained for x=0.75. We then successfully synthesized a series Heusler Fe2Co1-xCrxSi polycrystalline ribbon samples. The results of X-ray diffraction indicate that the Fe2Co1-xCrxSi series of samples are pure phase with a high degree of order and the saturation magnetic moment follows half-metallic Slater-Pauling rule. Except for the two end members, Fe2CoSi and Fe2CrSi, the anisotropic magnetoresistance of Fe2Co1-xCrxSi (x=0.25, 0.5, 0.75) show a negative value suggesting they are stable half-metallic ferromagnets.