Surface properties of the half- and full-Heusler alloys

Using a full-potential ab initio technique I study the electronic and magnetic properties of the (001) surfaces of the half-Heusler alloys NiMnSb, CoMnSb and PtMnSb and of the full-Heusler alloys Co2MnGe, Co2MnSi and Co2CrAl. The MnSb-terminated surfaces of the half-Heusler compounds present properties similar to those of the bulk compounds and, although the half-metallicity is lost, an important spin polarization at the Fermi level. In contrast to this, the Ni-terminated surface shows an almost zero net spin polarization. While the bulk Co2MnGe and Co2MnSi are almost half-ferromagnetic, their surfaces lose the half-metallic character and the net spin polarization at the Fermi level is close to zero. In contrast, the CrAl-terminated (001) surface of Co2CrAl shows a spin polarization of about 84%.