Magnetic and half-metallic properties of Co2(Cr1-xFex)Ga Heusler alloys have been investigated. In the entire concentration range, the L21-type ordered phase is obtained. The saturation magnetic moment Ms at 4.2K for x=0.0 (Co2CrGa) is 3.01μB/f.u., in agreement with the generalized Slater-Pauling line and consistent with the theoretical value. The experimental value of Ms increases with increasing x, slightly larger than that of the theoretical value above x=0.60. The Curie temperature TC also increases with x, and qualitatively accords with the theoretical values estimated from the effective exchange constant J0. The present theoretical results disclose that not only the L21-type ordered phase but also the B2-type phase exhibits high values of the spin polarization ratio P in a low concentration range of x. The ratio P of the L21- and B2-type phases decreases with increasing x, because the large peak of the density of states at the Fermi energy for Cr in the majority spin band becomes smaller and a strong hybridization between Co-3d and Fe-3d makes a gap narrower in the minority spin band.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2005 Dec 1