Magnetic properties of ZnO nanopowders
Magnetic properties of ZnO nanopowders
Xu, Q.; Zhou, S.; Schmidt, H.
We report the magnetic characterization of ZnO nanopowders with an average grain size of about 50 nm prepared by sol-gel method. At room temperature, ZnO nanopowders exhibit diamagnetism like bulk ZnO. However, strong paramagnetism was observed at 4 K. With increasing temperature, ferromagnetic to paramagnetic transition happens at around 90 K. Paramagnetism changes to diamagnetism at around 100 K, which is due to the competition between the paramagnetism from defects and diamagnetism from the bulk ZnO. Our work clearly demonstrates that the interaction betweeen the defects is short-range. Thus the interaction between the defects is weak due to low defect concentration. It is suggested that a high defect concentration is needed for room temperature ferromagnetism.
Keywords: Diluted magnetic semiconductor; ZnO; Magnetism; Defect
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Journal of Alloys and Compounds 487(2009), 665-667
DOI: 10.1016/j.jallcom.2009.08.033
Cited 70 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13072