Ferromagnetic copper-doped ZnO deposited on plastic substrates

Copper-doped ZnO (ZnO:Cu) films with Cu content of up to 8.2 at. % were prepared by filtered cathodic vacuum arc technique on plastic substrates. The ZnO:Cu films with 1.3 at. % of Cu exhibited the highest saturated magnetic moment of 0.28 μB/Cu. The binding species of the Zn 2p3/2, and Cu 2p3/2 peaks are located at around 1022.1 and 933.6 eV respectively, as measured by x-ray photoelectron spectroscopy respectively. This implies that the Cu ions in the films are mainly in divalent states. The magnetic anisotropy of the ZnO:Cu samples under strain were also studied by bending the flexible samples into various directions. The results indicate that strain plays a role in the magnetic anisotropy of the ZnO:Cu films. The electrical transport and annealing measurements of the ZnO:Cu films suggested that Zn interstitial defects have a significant role in the observed ferromagnetism in the ZnO:Cu. (Some figures in this article are in colour only in the electronic version) 1.