Prediction of half-metallic properties for the Heusler alloys Mn2CrZ (Z=Al, Ga, Si, Ge, Sb): A first-principles study

First-principles FLAPW calculations were performed on the Mn2CrZ (Z=Al, Ga, Si, Ge and Sb) alloys. Based on these results we predict two half-metallic ferromagnets (HMFs) namely Mn2CrAl and Mn2CrSb, and also find an energy gap in Mn2CrGa which lies near the Fermi level. The energy gap lies in the majority spin band for Mn2CrAl and Mn2CrGa, whereas in the minority one for Mn2CrSb. The calculated total spin magnetic moments Mtcal are −1μB per unit cell for Mn2CrAl and Mn2CrGa, +1μB per unit cell for Mn2CrSb and zero for Mn2CrSi and Mn2CrGe, 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.