Electronic structure, optical and ferromagnetic properties of ZnO co-doped with Ag and Co according to first-principles calculations

• Published in: Vacuum Vol. 173; p. 109127
• Main Authors: Liu, Yajing, Hou, Qingyu, Sha, Shulin, Xu, Zhenchao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2020
• Subjects: Ag and Co co-doped; First-principles; Optical and ferromagnetic properties; ZnO; ZnO; Optical and ferromagnetic properties; Ag and Co co-doped; First-principles
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2019.109127

First-principle calculations were performed to investigate the electronic structure, optical, and ferromagnetic properties of Ag/Co single- and co-doped ZnO. We found that both ZnO single-doped Ag and co-doped Ag/Co exhibit room-temperature ferromagnetism, whereas ZnO single-doped Co shows anti-ferromagnetism. Strongly enhanced room temperature ferromagnetism with saturate magnetization of 10.45 μB has been obtained in ZnO co-doped with Ag/Co, making it a promising room temperature ferromagnetic material. The magnetic moments of Ag/Co co-doped ZnO are mainly derived from the double-exchange effect between Co-3d state and O-2p state, which is consistent with Ruderman–Kittel–Kasuya–Yosida double exchange mechanism theory. In addition, Ag-doped ZnO undergoes a transition from magnetic to non-magnetic with the Ag doping concentration increasing from 2.77 mol% to 5.55 mol%. Ag/Co single- and co-doping can remarkly enhance absorption in the visible range. However, Ag single-doped ZnO has a long carrier lifetime and is conducive to the experimental design and preparation of new photocatalysts. Further research found that the interstitial hydrogen can induce the generation of magnetic order, reduce the magnetic moments and enhance the photocatalytic ability.
•A promising DMS of Ag-Co co-doped ZnO was obtained.•Ag single- and Ag-Co co-doped ZnO exhibit half-metallic p-type behavior.•The magnetic quenching mechanism of Ag-doped ZnO is explained.•Ag single-doped ZnO has the longest carrier lifetime.•The effect of Hi on ZnO is also discussed in this paper.