  We present an extended study of single impurity atoms at the interface
between the half-metallic ferromagnetic zinc-blende CrAs compound and the
zinc-blende binary InAs and CdSe semiconductors in the form of very thin
multilayers. Contrary to the case of impurities in the perfect bulk CrAs
studied in [I. Galanakis and S.G. Pouliasis, J. Magn. Magn. Mat. 321 (2009)
1084] defects at the interfaces do not alter in general the half-metallic
character of the perfect systems. The only exception are Void impurities at Cr
or In(Cd) sites which lead, due to the lower-dimensionality of the interfaces
with respect to the bulk CrAs, to a shift of the $p$ bands of the nearest
neighboring As(Se) atom to higher energies and thus to the loss of the
half-metallicity. But Void impurities are Schottky-type and should exhibit high
formation energies and thus we expect the interfaces in the case of thin
multilayers to exhibit a robust half-metallic character.
