First-principles study of spin-polarized electronic band structures in ferromagnetic Zn1−xTMxS (TM = Fe, Co and Ni)

We report a first-principles study of structural, electronic and magnetic properties of crystalline alloys Zn1−xTMxS (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 Zn1−xTMxS 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 3d states. Our results exhibit that Zn0.75Fe0.25S, Zn0.75Co0.25S and Zn0.75Ni0.25S are half-metallic ferromagnetic with a magnetic moment of 4μB, 3μB and 2μB, respectively. Furthermore, we calculate the TM 3d spin-exchange-splitting energies Δx (d), Δx (x−d), exchange constants N0α and N0β  , crystal field splitting (ΔEcryst≡Et2g−Eeg), and find that p–d hybridization reduces the local magnetic moment of TM from its free space charge value. Moreover, robustness of Zn1−xTMxS with respect to the variation of lattice constants is also discussed.

Research highlights▶ In this work we have reported a first-principles study of structural, electronic and magnetic properties of crystalline alloys Zn1−xTMxS (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 Zn1−xTMxS are greater than that of zincblende ZnS. ▶ Our results exhibit that Zn0.75Fe0.25S, Zn0.75Co0.25S and Zn0.75Ni0.25S are half-metallic ferromagnetic with a magnetic moment of 4μB, 3μB and 2μB, respectively. ▶ Furthermore, we calculate the TM 3d spin-exchange splitting energies Δx(d), Δx(p–d), exchange constants N0α and N0β  , crystal field splitting (ΔEcryst≡Et2g−Eeg), and find that p–d hybridization reduces the local magnetic moment of TM from its free space charge value. ▶ Moreover, robustness of Zn1−xTMxS with respect to the variation of lattice constants is also discussed.