First-principles study on the electronic structure of n-type magnetic semiconductor Ba(Zn Co )2As2

We perform systematic first-principles calculations on the electronic structure of n -type magnetic semiconductor Ba(Zn $_{1-x}$ Co _x ) _2 As _2 with the facilitation of HSE06 hybrid functional. Supercells are used to consider the doping of Co atoms, and the first-principles band structures are unfolded for clarity. Based on the calculation results, magnetic states are preferred by individual Co atoms doped in Ba(Zn $_{1-x}$ Co _x ) _2 As _2 at diluted limit, and carriers are originated mainly from situations where only one Co atom exists in the nearest neighbor Zn sites out of certain doped Co atoms. The origination of carriers can be explained by the density of states and the unfolded band structure, where it is found that the scattering effects from single Co atom is small but quite large when more Co atoms are located at adjacent Zn sites. The large scattering effects of two adjacent Co atoms will alter the band structures near the Fermi-level. Carriers in Ba(Zn $_{1-x}$ Co _x ) _2 As _2 mainly originate from the As-4p orbitals, with partial contributions from the Co-3d orbitals. Our work provides new insights into the origin of the n -type carriers in magnetic semiconductors and will inspire the development of new magnetic semiconducting systems.