Defect induced ferromagnetic ordering in epitaxial Zn0.95Mn0.05O films on sapphire (0 0 0 1)

Wei Rein Liu, Chih Wen Pao, Doris Weijyun Yu, Yi Ying Chin, Wen Bin Wu, Hong Ji Lin, Shu Chih Haw, Chia Hung Chu, Tzu Yang Chao, Hsu Cheng Hsu, Jin Ming Chen, Chia Hung Hsu, Wen Feng Hsieh, Chien Te Chen

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Abstract

We report the influence of Mn dopant on magnetic properties of Zn0.95Mn0.05O (ZMO)/Al2O3(0 0 0 1) hetero-epitaxial systems grown by using pulsed-laser deposition. The room temperature (RT) intrinsic ferromagnetic (FM) ordering verified by superconducting quantum interference device magnetometer and X-ray magnetic circular dichroism spectrum of Mn L 2,3 edges is ascribed to the substitutional Mn atoms in the Zn site of ZnO. Mn in ZMO has a tetrahedral local symmetry instead of the octahedral symmetry of MnO, after verifying the absence of the Mn-related impurities or clusters in ZMO epitaxial film by Mn K-edge and Zn K-edge X-ray absorption spectroscopy spectrum, as well as the analysis of long-range structural ordering on Renninger scan of forbidden (0 0 0 5) reflection in X-ray diffraction, transmission electron microscopy and Raman spectrum. Comparison of X-ray absorption spectra of ZMO with those of ZnO epilayers at O K-, Zn K-, and L 3-edges indicates that the substitution of the Zn site with Mn enhances the charge-transfer (CT) transition and the presence of Zn vacancies (VZn) also dominate the photoluminescence (PL) spectrum, implying that the formation of numerous VZn defects plays an important role in activating FM interactions. The strong CT effect and the existence of high-density VZn suggest that the intrinsic RT FM ordering of insulating ZMO is a result of the formation of the bound magnetic polarons (BMPs) that interact with each other via intermediate magnetic impurities.

Original languageEnglish
Article number485708
JournalJournal of Physics Condensed Matter
Volume31
Issue number48
DOIs
Publication statusPublished - 2019 Sep 6

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Liu, W. R., Pao, C. W., Yu, D. W., Chin, Y. Y., Wu, W. B., Lin, H. J., Haw, S. C., Chu, C. H., Chao, T. Y., Hsu, H. C., Chen, J. M., Hsu, C. H., Hsieh, W. F., & Chen, C. T. (2019). Defect induced ferromagnetic ordering in epitaxial Zn0.95Mn0.05O films on sapphire (0 0 0 1). Journal of Physics Condensed Matter, 31(48), [485708]. https://doi.org/10.1088/1361-648X/ab3b71