Prediction of half-metallic properties for the Heusler alloys Mn 2CrZ (Z=Al, Ga, Si, Ge, Sb): A first-principles study

Abstract

First-principles FLAPW calculations were performed on the Mn 2CrZ ( Z=Al, Ga, Si, Ge and Sb) alloys. Based on these results we predict two half-metallic ferromagnets (HMFs) namely Mn 2CrAl and Mn 2CrSb, and also find an energy gap in Mn 2CrGa which lies near the Fermi level. The energy gap lies in the majority spin band for Mn 2CrAl and Mn 2CrGa, whereas in the minority one for Mn 2CrSb. The calculated total spin magnetic moments M t cal are −1 μ B per unit cell for Mn 2CrAl and Mn 2CrGa, +1 μ B per unit cell for Mn 2CrSb and zero for Mn 2CrSi and Mn 2CrGe, which agree with the Slater–Pauling rule. The calculation indicates a large and localized magnetic moment of Cr at B site. This is meaningful for searching for new half-metallic antiferromagnets in Heusler alloys. The magnetic moment of Cr is found to increase with increasing atomic number of Z and is antiparallel to that of Mn. The change of Mn and Cr spin moments compensates each other and keeps the total spin moment as an integer when the Z atom is changed.