Activation of high-Tc ferromagnetism in Mn2+-doped ZnO using amines

We report the discovery that high-TC ferromagnetism in manganese-doped ZnO (Mn2+:ZnO) can be activated by amine binding and calcination. The activation of ferromagnetism is attributed to the incorporation of uncompensated p-type dopants into the ZnO lattice upon amine calcination, a process that has substantial precedence in the literature surrounding p-type ZnO. The experimental observations are consistent with a microscopic mechanism involving formation of bound magnetic polarons upon introduction of p-type dopants into Mn2+:ZnO. These results clearly demonstrate that Mn2+:ZnO ferromagnetism is critically sensitive to defects other than the magnetic dopants themselves, offering some insight into the diversity of experimental observations reported previously for this material. Copyright © 2005 American Chemical Society.