Co location and valence state determination in ferromagnetic ZnO : Co thin films by atom-location-by-channeling-enhanced-microanalysis electron energy-loss spectroscopy

The Co valence state and the location of Co dopant atoms in ZnO:Co thin films revealing anomalous Hall effect below 50 K have been determined by electron energy-loss spectroscopy (EELS) measurements and atom location by channeling enhanced microanalysis (ALCHEMI), respectively. The method of ALCHEMI-EELS to investigate the dopant in materials was brought. It was used to determine that the intrinsic ferromagnetism in ZnO:Co thin films derives from the +2 Co which substitute for Zn atoms at Zn sites in the ZnO matrix. The divalent Co state in ZnO:Co has been unambiguously proven by modeling the corresponding EELS data.