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

Assa Aravindh Sasikala Devi, Iman S. Roqan

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

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. © 2016 The Royal Society of Chemistry.
Original languageEnglish (US)
Pages (from-to)50818-50824
Number of pages7
JournalRSC Adv.
Volume6
Issue number56
DOIs
StatePublished - 2016

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