Electronic structures and optical properties of the new diluted magnetic semiconductors Fe-doped LiZnP

Using the first-principle density functional theory based on the full potential linearized augmented plane wave method, the geometric structures of new diluted magnetic semiconductor Li_1±y (Zn_1-xFe_x)P (x = 0, 0.0625; y = 0, 0.0625) were optimized. The electronic structures, half-metallic properties, formation energies and optical properties were calculated and discussed in details. The results show that the doping of Fe causes the system to produce a spin-polarized impurity band. The densities of Fe 3d, Li 2s, Zn 4s and P 3p states overlap at the Fermi level, leading to sp-d orbital hybridization. The system has the biggest magnetic moment and exhibits metallicity, its conductivity is enhanced. When Li is insufficient, the conductivity is weakened, but the impurity band width and the Curie temperature increases. While the excess of Li makes the formation energy reduce. The material becomes half-metallic and exhibits 100% spin injection. The magnetic and electrical properties of the doped system can be regulated by the incorporation of Fe and off-stoichiometry of Li respectively. Comparing optical properties indicate that the imaginary part of the dielectric function and complex refractive index function of Li insufficient system both have new peaks in the low energy region, which enhances the absorption of low frequency electromagnetic waves. The energy loss functions of the doped systems show obvious blue-shift, and the oscillating range of plasma becomes wider in Li excess compounds. (authors)