Magnetization and Raman scattering studies of (Co,Mn) codoped ZnO nanoparticles

Single-phase (Co,Mn) codoped ZnO nanoparticles were synthesized by an autocombustion method. Hysteresis loop was observed at 300 K for the sample $Zn0.98Co0.01Mn0.01O$ with a low coercivity $(40±5Oe)$⁠. Temperature dependence of magnetization rules out the possibility of superparamagnetism or spin-glass behavior. Raman scattering studies manifested that there might exist a defect annihilation arising from the (Co,Mn) codoped into ZnO host lattice. As the ferromagnetism of diluted magnetic semiconductors is closely related to the dopant-defect hybridization, the ferromagnetic ordering was significantly enhanced in the sample $Zn0.98Co0.01Mn0.01O$ by the (Co,Mn) codoping, in comparison to the $Zn0.99Co0.01O$ and $Zn0.99Mn0.01O$ fabricated by the same method.