a b s t r a c tThe structure stability, electronic structure and magnetic properties of zinc-blende Be 15 TMTe 16 (TM ¼ Cr, Mn, Fe, Co and Ni) diluted magnetic semiconductors have been investigated using first-principles calculations. The Be 15 CrTe 16 and Be 15 FeTe 16 compounds are found to be half-metallic, and Be 15 MnTe 16 and Be 15 CoTe 16 compounds are found to be semiconducting, while Be 15 NiTe 16 is confirmed to be metallic. And the results indicate that these five compounds should be stable and may be synthesized in practice. These results suggest a possibility that Be 15 CrTe 16 and Be 15 FeTe 16 can be applied in the spintronic field.

With the first-principles method based on the density functional theory (DFT), we study the effect of defects on Cu-doped CdS. A single Cd vacancy, S vacancy or Cd interstitial is inserted into the Cd34Cu2S36 crystal structure, respectively. Band structures and the density of states (DOS) are calculated to investigate the effect of various defects on the electronic structures, which are considered to be associated with magnetic properties and optical properties. It turns out that the Cd vacancy, S vacancy and Cd interstitial have a significant influence on the ferromagnetic (FM) stability and optical properties. These results provide an approach to utilize Cu-doped CdS-based materials used as spintronics and optoelectronic devices efficiently.