Structural and magnetic properties of ZnO:TM (TM: Co, Mn) nanopowders

We report on the structural and magnetic characterization of Co0.1Zn0.9OCo0.1Zn0.9O and Mn0.1Zn0.9OMn0.1Zn0.9O nanopowders obtained by a soft chemistry route. We show that those samples fired at low temperatures display a ferromagnetic interaction that cannot be attributed to the presence of impurities. A magnetic aging mechanism is observed, reflecting the key role played by defects in the stabilization of ferromagnetism in this kind of diluted magnetic semiconductors.