Many-body quasiparticle spectrum of Co-doped ZnO: A GW perspective

Abstract

In transition-metal-doped ZnO the energy position of the dopant 3 d states relative to the host conduction and valence bands determines the possibility of long-range ferromagnetism. Density functional theory (DFT) can estimate the energy position of the Co-3 d states in ZnO:Co but this depends substantially upon the choice of exchange-correlation functional. In this paper we investigate many-body GW corrections built on top of DFT + U and hybrid-DFT ground states to provide a theoretical benchmark for the quasiparticle energies in wurtzite ZnO:Co. Both single shot G 0 W 0 as well as partially self-consistent GW 0 , wherein the wave functions are held fixed at the DFT level but the eigenvalues in G are iterated, are considered. The predicted energy position of the minority spin Co- t 2 states is 3.0?3.6 eV above the ZnO conduction band minimum, which is closer to hybrid-DFT-based estimates. Such an electronic structure does not support carrier-mediated long-range ferromagnetism at achievable n -doping conditions