First-principles study on the electronic and magnetic properties of the Zn0.75Mo0.25M(M = S,Se,Te)

The geometrical, electronic and magnetic properties of the Zn0.75Mo0.25M (M=S, Se and Te) have been studied by spin-polarized first-principles calculation. The optimized lattice constants of 5.535, 5.836 and 6.274 A for M=S, Se and Te are related to the atomic radius of 1.09, 1.22 and 1.42 A for S, Se and Te atoms, respectively. The Zn0.75Mo0.25M are magnetic half-metallic (HM) with the spin-down conventional band gaps of 2.899, 2.126 and 1.840 eV, while the HM band gaps of 0.393, 0.016 and 0.294 eV for M=S, Se and Te, respectively. At the Fermi level, the less than half-filled Mo-4d orbital hybridizated with the less M-p orbital contributes only spin-up channel leading Zn0.75Mo0.25M an HM ferromagnetism. The tetrahedral crystal field formed by adjacent three Zn atoms and one M atom splits the spin-up channel (majority spin) of Mo-4d orbital into three-fold degenerate t2g(dxy,dyz,dzx) states at the Fermi level and double degenerate eg (dz2,dx2−y2) states below the Fermi level. The exchange splitting energies of the Zn0.75Mo0.25M are −2.611, −2.231 and −1.717 eV for M=S, Se and Te, respectively. The results provide an useful theoretical guidance for Zn0.75Mo0.25M applications in spintronic devices.