Adsorption of H on the ZnO(0001) Surface and d0 Magnetism: An Ab Initio Study

Abstract

Ab initio total energy calculations were performed to study the adsorption of atomic hydrogen on the polar surface of Zn–ZnO(0001) for different degrees of surface coverage. The most stable configuration was calculated as a function of the distance between H and the surface. The present results show that the manifest ferromagnetism depends on purely surface interactions. It involves charge transfer from the H-1s level to the Zn-4s level, leading to a magnetic moment of 1.0 μ_B for full H surface coverage in the supercell. The magnetic interaction between H atoms is ferromagnetic. In addition, for a fully hydrogenated ZnO monolayer with zinc vacancies (V_Zn) or hydrogen-passivated zinc vacancies (V_Zn–H), a transition from a nonmagnetic semiconductor to a magnetic half-metal semiconductor has been achieved. Both configurations exhibit a surface magnetic moment of 2.0 μ_B, which is twice that obtained for the case without the vacancy. These theoretical calculations agree with our previously published experimental results, where it was observed that hydrogen is incorporated into the ZnO structure and acts as a surface donor.