Effects of Li ion implantation energies on the structure, photoluminescence, and ferromagnetism properties of (Li, Co) co-implanted ZnO films |
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Authors: | CW ZouJ Zhang W XieLX Shao LP GuoDJ Fu |
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Affiliation: | a Department of Physics and Development Center for New Materials Engineering and Technology in Universities of Guangdong, Zhanjiang Normal University, Zhanjiang 524048, China b Accelerator Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China |
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Abstract: | Room temperature ferromagnetism was observed in (Li, Co) co-implanted ZnO films. The implantation energy for Co ions was 400 keV, while for Li ions were 50, 100 and 200 keV, respectively. The ion implantation induced defects and disorder has been observed by the XRD, PL and TEM experiments. For the co-implanted ZnO films with Li ion implantation energies of 100 and 200 keV, the band energy emission disappears and the defect related emission with wavelength of 500-700 nm dominates, which can be attributed to defects introduced by implantation. Co-implanted ZnO Films with Li ion implantation energies of 200 keV show a saturation magnetization value (MS) of over 9 × 10−5 emu and a positive coercive field of 60 Oe. The carrier concentration is not much improved after annealing and in the order of 1016 cm−3, which suggests that FM does not depend upon the presence of a significant carrier concentration. The origin of ferromagnetism behavior can be explained on the basis of electrons and defects that form bound magnetic polarons, which overlap to create a spin-split impurity band. |
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Keywords: | Ferromagnetism Microstructure Ion implantation ZnO |
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