Evidence of room-temperature ferromagnetism in vertically aligned Bi–Co co-doped ZnO nanowires

Kazmi, Jamal and Ooi, Poh Choon and Raza, Syed Raza Ali and Goh, Boon Tong and Karim, Siti Shafura A and Samat, Mohd Hazrie and Lee, Min Kai and Mohd, M F and Wee, Razip and Taib, Mohamad Fariz Mohamad and Mohamed, Mohd Ambri (2021) Evidence of room-temperature ferromagnetism in vertically aligned Bi–Co co-doped ZnO nanowires. Journal of Physics D: Applied Physics, 54 (41). p. 415301. ISSN 0022-3727, DOI https://doi.org/10.1088/1361-6463/ac0b6f.

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Official URL: https://doi.org/10.1088/1361-6463/ac0b6f


We are the first to report Bi-Co co-doped zinc oxide nanowires (ZnO NWs) to investigate theoretically and experimentally the alignment of relative spin and the location of Bi3+ and Co2+ as the primary cause of magnetism. In the present study, we carefully performed theoretical and experimental studies of ZnO NWs prepared by the hydrothermal method and obtained exciting outcomes. The x-ray diffraction findings show that the NWs have a wurtzite crystal structure and high intensity at the (002) peak, indicating that most of the reflection comes from the hexagonal surface of the NWs. This means that the extended NWs are mainly aligned along the c-axis. The field-emission scanning electron microscope results show that, due to its anisotropic crystal existence, the grown NWs have a preferred path along the c-axis in the (001) direction. X-ray photoelectron spectroscopy studies established the presence of both Bi and Co in all the Bi-Co co-doped samples. They also showed that OH- groups exist on the surface of ZnO NWs, and increasing Co content tends to increase the O-deficient region in the ZnO matrix. UV-vis analysis showed a decreased optical band gap upon doping, which is probably due to the sp-d exchange interaction between localized d-electron bands of dopants. Optical studies also suggested that the doping induced an increase in electron concentration. The Raman results indicate that the ZnO NWs contain crystallization with few defects after Bi-Co-doping. From the magnetic studies, it was observed that the ferromagnetism probably originates from the defect-rich regions, i.e. NW surface and Bi and Co sit at ZnO's substitutional site. In contrast, the core of the NWs remains under the other magnetic state. Our density functional theory studies are in line with the experimental results.

Item Type: Article
Uncontrolled Keywords: Zinc oxide nanowires; Bi-Co co-doped; Hydrothermal synthesis; Magnetic non-magnetic dopant; Diluted magnetic semiconductor; Room temperature ferromagnetism
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Divisions: Faculty of Science
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 18 Feb 2022 01:46
Last Modified: 18 Feb 2022 01:46
URI: http://eprints.um.edu.my/id/eprint/26283

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