Half-metallic properties for the Mn2 FeZ (Z=Al, Ga, Si, Ge, Sb) Heusler alloys: A first-principles study

The electronic structure and magnetism of the Mn2 FeZ (Z=Al, Ga, Si, Ge, Sb) Heusler alloys have been studied by density functional calculations. Two half-metallic ferromagnets, namely, Mn2 FeAl and Mn2 FeSb, are predicted. It is found that a small expansion of the crystal lattice can restore the half-metallicity in Mn2 FeSi. The calculated total magnetic moments Mtot are 1 μB /f.u. for Mn2 FeAl and Mn2 FeGa, 2 μB /f.u. for Mn2 FeSi and Mn2 FeGe, and 3 μB /f.u. for Mn2 FeSb, which agree with the Slater-Pauling curve quite well. The moments of Mn (A) and Mn (B) are large and antiparallel to each other, which is indicative of ferrimagnetism in Mn2 FeZ alloys. Fe shows only a small moment and its moment is parallel to that of Mn (B). By investigating the effect of lattice distortion on the half-metallicity and magnetic moments of Mn2 FeZ, it is found that the half-metallic properties of Mn2 FeSb are insensitive to the lattice distortion and a 100% spin polarization can be obtained within the wide range of 5.4-6.05 Å. This is preferable in practical applications.