First principle study of Co2MnSi/GaAs(001) heterostructures

We have studied the electronic and magnetic properties of Co2MnSi/GaAs(001) heterostructure within the framework of the density functional theory by using the plane wave pseudopotential approach, with the aim of identifying possible interface morphologies where the peculiar half-metallic character of the constituent Heusler alloy is conserved. Among the different possible patterns, for the ideal abrupt SiMn/As interface we have identified two geometries characterized by high symmetry and low formation energy, corresponding to (a) both Si and Mn atoms in bridge sites between As and to (b) Si atoms on top of As and Mn atoms at hollow sites. The former one is particularly promising for spin injection, showing a spin polarization of 100% also at interface. We investigated also the corresponding Mn-rich interfaces, obtained from the ideal ones by substituting interfacial Si atoms by Mn, i.e., MnMn/As. In such a case, spin polarization is fully conserved at the other interface pattern. Band alignments for the majority and minority spin channels are also discussed. (C) 2007 American Institute of Physics.