The need for spin-injectors having the same zinc-blende-type crystal structure as conventional semiconductor substrates has created significant interests in theoretical predictions of possible metastable “half-metallic” zinc-blende ferromagnets, which are normally more stable in other structure-types, e.g., NiAs. Such predictions were based in the past on differences ${\Delta }_{\text{bulk}}$ in the total energies of the respective bulk crystal forms (zinc blende and NiAs). We show here that the appropriate criterion is comparing difference ${\Delta }_{\mathrm{epi}}\left(a_s\right)$ in epitaxial total energies. This reveals that even if ${\Delta }_{\text{bulk}}$ is small, still for MnAs, CrSb, CrAs, CrTe, ${\Delta }_{\mathrm{epi}}\left(a_s\right)>0$ for all substrate lattice constant $a_s$, so the zinc-blende phase is not stabilized. For CrS we find ${\Delta }_{\mathrm{epi}}\left(a_s\right)<0$, but the system is antiferromagnetic, thus not half-metallic. Finally, zinc-blende CrSe is predicted to be epitaxially stable for $a_s>6.2\mathrm{\AA }$ and is half metallic.

• Received 21 November 2004

DOI:https://doi.org/10.1103/PhysRevB.71.132403