Comparative study of CdTe bulk system co-doped with two different transition metal atoms using different exchange-correlation energy functionals: GGA, GGA+U and Hybrid Functional

We have examined the half-metallic (HM) nature of CdTe bulk zinc-blende structure co-doped with two different 3d transition metal (TM) atoms: one Mn and the other X (X = V, Cr, Mn, Fe and Ni) atom using first principles full potential linearized augmented plane-wave (FP-LAPW) method as implemented in Wien2K code. Different exchange-correlation energy functionals namely generalized gradient approximation (GGA), GGA+U (Hubbard Coulomb onsite correction) and hybrid functionals are used to confirm the robustness of half-metallic (HM) character of the structure. Mn-Cr and Mn-Ni co-doped systems turn out to be HM with GGA+U. However, these systems finally turn into a semiconductor with the use of hybrid functional as the d states of Cr and Ni atoms are pushed down in the valence region creating a gap at the Fermi level.