Half-metallic properties of CoS2, doped CoN0.25S1.75 and CoP0.25S1.75

We use first-principles calculations to investigate the half-metallicity of pure CoS2, doped CoN0.25S1.75 and CoP0.25S1.75 systems. The results show that the conduction bands minimum (CBM) of pure CoS2 is mainly contributed by the low intensity state of S ppσ∗ in the spin-down channel. The S ppσ∗ state extends below the Fermi level (EF) and destroys the half-metallicity of CoS2, rather than Co-eg↓ states proposed previously. Replacing sulfur (S) with nitrogen (N) reduces the bandwidth of the S (N) ppσ∗ bands and destroys the continuous S ppσ∗ network, as a result the bottom of the S ppσ∗ band shifts upward above the bottom of the Co-eg↓ band and makes the CoN0.25S1.75 a perfect half metal ferromagnet (HMF) and a promising candidate for spintronic devices.