Room-temperature ferromagnetism of Cu-doped ZnO films probed by soft x-ray magnetic circular dichroism

T. S. Herng, D. C. Qi, T. Berlijn, J. B. Yi, K. S. Yang, Y. Dai, Y. P. Feng, I. Santoso, C. Sánchez-Hanke, X. Y. Gao, Andrew T.S. Wee, W. Ku, J. Ding, A. Rusydi

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211 Scopus citations

Abstract

We report direct evidence of room-temperature ferromagnetic ordering in O-deficient ZnO:Cu films by using soft x-ray magnetic circular dichroism and x-ray absorption. Our measurements have revealed unambiguously two distinct features of Cu atoms associated with (i) magnetically ordered Cu ions present only in the oxygen-deficient samples and (ii) magnetically disordered regular Cu2⊃+ ions present in all the samples. We find that a sufficient amount of both oxygen vacancies (VO) and Cu impurities is essential to the observed ferromagnetism, and a non-negligible portion of Cu impurities is uninvolved in the magnetic order. Based on first-principles calculations, we propose a microscopic "indirect double-exchange" model, in which alignments of localized large moments of Cu in the vicinity of the VO are mediated by the large-sized vacancy orbitals.

Original languageEnglish
Article number207201
JournalPhysical Review Letters
Volume105
Issue number20
DOIs
StatePublished - Nov 8 2010
Externally publishedYes

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