First-principles study of spin-polarized electronic band structures in ferromagnetic Zn 1− xTM xS (TM = Fe, Co and Ni)

Abstract

We report a first-principles study of structural, electronic and magnetic properties of crystalline alloys Zn 1− x TM x S (TM = Fe, Co and Ni) at x = 0.25. Structural properties are computed from the total ground state energy convergence and it is found that the cohesive energies of Zn 1− x TM x S are greater than that of zincblende ZnS. We also study the spin-polarized electronic band structures, total and partial density of states and the effect of TM 3 d states. Our results exhibit that Zn 0.75Fe 0.25S, Zn 0.75Co 0.25S and Zn 0.75Ni 0.25S are half-metallic ferromagnetic with a magnetic moment of 4 μ B, 3 μ B and 2 μ B, respectively. Furthermore, we calculate the TM 3 d spin-exchange-splitting energies Δ x ( d), Δ x ( x− d), exchange constants N 0 α and N 0 β, crystal field splitting ( Δ E cryst ≡ E t 2 g − E e g ) , and find that p– d hybridization reduces the local magnetic moment of TM from its free space charge value. Moreover, robustness of Zn 1− x TM x S with respect to the variation of lattice constants is also discussed.