Electronic, Structural and Magnetic Properties of Light Transition-Metal Doped Wurtzite Cadmium Sulfide

摘要

The electronic, structural and magnetic properties of light-transition-metal element (TM = Sc, V, Ti, Cr and Mn) doped cadmium sulfide Cd_(1-x)TM_xS are studied using spin-polarized density function theory. The Perdew Burke Ernzerhof (PBE) exchange and correlation functional is employed within the generalized gradient approximation (GGA). Our results show that the substitutional Sc~(2+), V~(2+), Ti~(2+), Mn~(2+) and Cr~(2+) magnetic ions can easily be incorporated on cation sites of the host lattice of CdS and induce spin polarized localized states in the gap or near the conduction band and generate local magnetic moments on doped atoms with values 0.527 μ_B, 1.723 μ_B, 2.752 μ_B, 3.766 μ_B and 4.471 μ_B respectively. The spin exchange splitting energy Δ_xd increases consistently with increase in atomic number of the dopant. The values of Δ_x(pd) are negative for Cr and Mn and positive for Sc, Ti and V. It means that the effective potential for minority spin states is more attractive than that of majority spin states for Cr and Mn and vice versa for Sc, Ti and V. The s-d exchange constant N_oα and pd exchange constant N_oβ are showing the magnetic nature of these TM-doped CdS compounds. It is observed that p-d hybridization reduces the local magnetic moment of the doped CdS from its free space charge value and produces small local magnetic moments on the nonmagnetic Cd and S host sites. CdS provides us a variety of compounds, doping of Sc, Ti and V forms degenerate semiconductors, Cr forms half metallic and Mn p-type semiconductor. For degenerated semiconductors we have calculate the Burstein-Moss shift energy.