Cu-substituted ZnO thin films are known to exhibit room-temperature ferromagnetism. Herein, we report a large enhancement of ferromagnetism in nanoparticles of Zn1−xCuxO (CZOs) at x ∼ 1/8. In addition to the magnetic moment arising from the Cu 3d9 spins, these nanoparticles provide a unique platform to produce a significant number of oxygen vacancies (VOs), which gives rise to a long-range ferromagnetic order due to the interaction with the spins of Cu 3d9 through the oxygen vacancies and Cu 3d9 ligand holes. Interestingly, the highest magnetization occurs in CZO with x ≈ 0.13. Thus, our results emphasize the importance of the interplay between the Cu 3d9 spins with oxygen vacancies and Cu 3d9 ligand holes in generating a long-range ferromagnetic order.
- Cu-substituted ZnO
- Dilute magnetic semiconductor
- Oxygen vacancies