Room-Temperature Ferromagnetism of Cu-Doped ZnO Films Probed by Soft X-Ray Magnetic Circular Dichroism Academic Article uri icon

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 (V(O)) 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 V(O) are mediated by the large-sized vacancy orbitals.

authors

  • Herng, TS
  • Qi, D-C
  • Berlijn, T
  • Yi, JB
  • Yang, KS
  • Dai, Y
  • Feng, YP
  • Santoso, I
  • Sánchez-Hanke, C
  • Gao, XY
  • Wee, Andrew TS
  • Ku, W
  • Ding, J
  • Rusydi, A

publication date

  • November 8, 2010