Issue 56, 2016

The origin of room temperature ferromagnetism mediated by Co–VZn complexes in the ZnO grain boundary

Abstract

Ferromagnetism in polycrystalline ZnO doped with Co has been observed to be sustainable in recent experiments. We use first-principle calculations to show that Co impurities favorably substitute at the grain boundary (GB) rather than in the bulk. We reveal that room-temperature ferromagnetism (RTFM) at the Co-doped ZnO GB in the presence of Zn vacancies is due to ferromagnetic exchange coupling of a pair of closely associated Co atoms in the GB, with a ferromagnetic exchange coupling energy of ∼300 meV, which is in contrast to a previous study that suggested the O vacancy–Co complex induced ferromagnetism. Electronic structure analysis was used to predict the exchange coupling mechanism, showing that the hybridization of O p states with Co and Zn d states enhances the magnetic polarization originating from the GB. Our results indicate that RTFM originates from Co clusters at interfaces or in GBs.

Graphical abstract: The origin of room temperature ferromagnetism mediated by Co–VZn complexes in the ZnO grain boundary

Associated articles

Article information

Article type
Paper
Submitted
08 May 2016
Accepted
18 May 2016
First published
19 May 2016

RSC Adv., 2016,6, 50818-50824

The origin of room temperature ferromagnetism mediated by Co–VZn complexes in the ZnO grain boundary

A. A. Sasikala Devi and I. S. Roqan, RSC Adv., 2016, 6, 50818 DOI: 10.1039/C6RA11607H

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