Magnetic order in Co-doped and (Mn, Co) codoped ZnO thin films by pulsed laser deposition

Co-doped ${\mathrm{Zn}}_{\text{1−x}}{\mathrm{Co}}_x{\mathrm{Al}}_{\text{0.01}}\mathrm{O}$ $\text{(x=0.15,0.3)}$ and (Mn, Co) codoped ${\mathrm{Zn}}_{\text{0.7}}({\mathrm{Mn}}_{\text{0.15}}{\mathrm{Co}}_{\text{0.15}})\mathrm{O}$ thin films were fabricated on ${\mathrm{Al}}_2{\mathrm{O}}_3$ (0001) by pulsed laser deposition. The doped ZnO thin films with well wurtzite structures could be deposited at a low temperature of 400 °C and low oxygen pressure of ${\text{5×10}}^{\text{−5}}\hspace{0.17em}\mathrm{Pa}.$ The Co-doped ZnO showed metallic conductivity with low resistance, while the (Mn, Co) codoped ZnO was semiconductor with high resistance, which was confirmed by the resistance vs temperature measurements. All the three doped ZnO films showed room temperature (290 K) ferromagnetism, with the saturated magnetic moments of ${\text{0.08μ}}_B/\mathrm{Co},$ ${\text{0.17μ}}_B/\mathrm{Co},$ and ${\text{0.19μ}}_B\text{/(0.5}\mathrm{Co}\text{+0.5}\mathrm{Mn})$ for ${\mathrm{Zn}}_{\text{0.85}}{\mathrm{Co}}_{\text{0.15}}{\mathrm{Al}}_{\text{0.01}}\mathrm{O},$ ${\mathrm{Zn}}_{\text{0.7}}{\mathrm{Co}}_{\text{0.3}}{\mathrm{Al}}_{\text{0.01}}\mathrm{O},$ and ${\mathrm{Zn}}_{\text{0.7}}({\mathrm{Mn}}_{\text{0.15}}{\mathrm{Co}}_{\text{0.15}})\mathrm{O},$ respectively.