Magnetic Properties of Fe/Cu Codoped ZnO Nanocrystals
2012 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, Vol. 3, no 15, 2009-2014 p.Article in journal (Refereed) Published
Free-standing ZnO nanocrystals simultaneously doped with Fe and Cu with varying Fe/Cu compositions have been synthesized using colloidal methods with a mean size of similar to 7.7 nm. Interestingly, while the Cu-doped ZnO nanocrystal remains diamagnetic and Fe-doped samples show antiferromagnetic interactions between Fe sites without any magnetic ordering down to the lowest temperature investigated, samples doped simultaneously with Fe and Cu show a qualitative departure in exhibiting ferromagnetic interactions, with suggestions of ferromagnetic order at low temperature. XAS measurements establish the presence of Fe2+ and Fe3+ ions, with the concentration of the trivalent species increasing in the presence of Cu doping, providing direct evidence of the Fe2+ + Cu2+ sic Fe3+ + Cu+ redox couple being correlated with the ferromagnetic property. Using DFT, the unexpected ferromagnetic nature of these systems is explained in terms of a double exchange between Fe atoms, mediated by the Cu atom, in agreement with experimental observations.
Place, publisher, year, edition, pages
2012. Vol. 3, no 15, 2009-2014 p.
IdentifiersURN: urn:nbn:se:uu:diva-184662DOI: 10.1021/jz300741zISI: 000309691500014OAI: oai:DiVA.org:uu-184662DiVA: diva2:567124