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 Mn(2)FeZ (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 1 mu(B)/f.u. for Mn2FeAl and Mn2FeGa, 2 mu(B)/f.u. for Mn2FeSi and Mn2FeGe, and 3 mu(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 Mn(2)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 Mn(2)FeZ, 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 angstrom. This is preferable in practical applications. (c) 2008 American Institute of Physics.