%0 Journal Article
%A Galanakis, I.
%A Özdogan, K.
%A Sasioglu, E.
%T Ab initio electronic and magnetic properties of half-metallic NiCrSi and NiMnSi Heusler alloys: The role of defects and interfaces
%J Journal of applied physics
%V 104
%@ 0021-8979
%C Melville, NY
%I American Institute of Physics
%M PreJuSER-3110
%P 083916
%D 2008
%Z Record converted from VDB: 12.11.2012
%X Using state-of-the-art first-principles calculations, we study the properties of the ferromagnetic Heusler compounds NiYSi, where Y stands for V, Cr, or Mn. NiCrSi and NiMnSi contrary to NiVSi are half-metallic at their equilibrium lattice constant exhibiting integer values of the total spin magnetic moment, and thus we concentrate on these two alloys. The minority-spin gap has the same characteristics as for the well-known NiMnSb alloy being around similar to 1 eV. Upon tetragonalization, the gap is present in the density of states even for expansion or contraction of the out-of-plane lattice parameter by 5%. The Cr-Cr and Mn-Mn interactions make ferromagnetism extremely stable and the Curie temperature exceeds 1000 K for NiMnSi. Surface and interfaces with GaP, ZnS, and Si semiconductors are not half-metallic but, in the case of NiCrSi, the Ni-based contacts present spin polarization at the Fermi level around 90%. Finally, we show that there are two cases of defects and atomic-swaps. The first ones, which involve the Cr (Mn) and Si atoms, induce states at the edges of the gap, which persists for a moderate concentration of defects. Defects involving Ni atoms induce states localized within the gap completely destroying the half-metallicity. Based on single-impurity calculations, we associate these states to the symmetry of the crystal. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3005882]
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000260572100078
%R 10.1063/1.3005882
%U https://juser.fz-juelich.de/record/3110