Structural and magnetic properties of ZnO:TM (TM: Co,Mn) nanopowders
  We report on the structural and magnetic characterization of Co0.1Zn0.9O and Mn0.1Zn0.9O nanopowders obtained by a soft chemistry route. We show that those samples fired at low temperatures display a ferromagnetic interaction that can not 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. 
D. Rubi, A. Calleja, J. Arbiol, X.G. Capdevila, M. Segarra, Ll.   Aragones and J. Fontcuberta