Search for new half-metallic ferromagnets in semi-Heusler alloys NiCrM (M = P, As, Sb, S, Se and Te)

The first-principles calculation within density-functional theory is used to search for new candidates of half-metallic ferromagnets in semi-Heusler alloys NiCrM (M P, As, Sb, S, Se and Te). Our calculations predict that NiCrP, NiCrSe and,NiCrTe are half-metallic ferromagnets (HMFs) with magnetic moments of nearly 3 or 4 mu(B)/fu and HM gaps of 0.263, 0.047 and 0.102 eV, respectively. Other compounds are so-called nearly HMFs. Substitution of the sp atoms cannot be responsible. for the formation of the band gap, but. results in a shift in the Fermi level and the loss of half-metallicity. The half-metallicity of NiCrP and NiCrTe can be retained when the lattice. parameter is changed by about 2%-3%.