Half-metallic properties for the Mn2FeZ (Z=Al, Ga, Si, Ge, Sb) Heusler alloys: A first-principles study.

The electronic structure and magnetism of the Mn₂FeZ (Z=Al, Ga, Si, Ge, Sb) Heusler alloys have been studied by density functional calculations. Two half-metallic ferromagnets, namely, Mn₂FeAl and Mn₂FeSb, are predicted. It is found that a small expansion of the crystal lattice can restore the half-metallicity in Mn₂FeSi. The calculated total magnetic moments M_tot are 1μ_B/f.u. for Mn₂FeAl and Mn₂FeGa, 2μ_B/f.u. for Mn₂FeSi and Mn₂FeGe, and 3μ_B/f.u. for Mn₂FeSb, 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 Mn₂FeZ 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 Mn₂FeZ, it is found that the half-metallic properties of Mn₂FeSb 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. [ABSTRACT FROM AUTHOR]