High-Pressure and Temperature Synthesized Co-Doped ZnO Based DMSs

High-pressure and high-temperature are used to treat a series of Co doped ZnO samples synthesized by Sol-gel method.Structure and composition analyses suggest that CoO is formed after increasing the Co concentration under the high-pressure condition.The results of magnetism measurements by SQUID show that all the samples have room-temperature ferromagnetism and the ferromagnetism increases as the Co doping concentration increases,despite the formation of antiferromagnetic CoO under the high pressure condition.Thus,we argue that the ferromagnetism of ZnCoO is intrinsic.