Defect induced room temperature ferromagnetism in high quality Co-doped ZnO bulk samples

JOURNAL OF ALLOYS AND COMPOUNDS

卷:859

Article

de Godoy, M. P. F.¹  Gratens, X.²  Chitta, V. A.²  Mesquita, A.³  de Lima Jr, M. M.⁴  Cantarero, A.⁵  Rahman, G.⁶  Morbec, J. M.⁷  de Carvalho, H. B.⁸ 

[1] Univ Fed Sao Carlos UFSCar, Dept Fis, BR-13565905 Sao Carlos, Brazil

[2] Univ Sao Paulo, Inst Fis, BR-05508090 Sao Paulo, Brazil

[3] Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, Dept Fis, UNESP, BR-13500900 Rio Claro, Brazil

[4] Univ Valencia, Mat Sci Inst, E-46071 Valencia, Spain

[5] Univ Valencia, Inst Mol Sci, E-46071 Valencia, Spain

[6] Quaid I Azam Univ, Dept Phys, Islamabad 45320, Pakistan

[7] Keele Univ, Sch Chem & Phys Sci, Keele ST5 5BG, Staffs, England

[8] Univ Fed Alfenas UNIFAL, BR-37130000 Alfenas, Brazil

关键词: Doped oxides;    Defect engineering;    Ferromagnetism;    Spintronics;   

DOI  :  10.1016/j.jallcom.2020.157772

来源: Elsevier

【 摘 要 】

The nature of the often reported room temperature ferromagnetism in transition metal doped oxides is still a matter of huge debate. Herein we report on room temperature ferromagnetism in high quality Co-doped ZnO (Zn1-xCoxO) bulk samples synthesized via standard solid-state reaction route. Reference paramagnetic Co-doped ZnO samples with low level of structural defects are subjected to heat treatments in a reductive atmosphere in order to introduce defects in the samples in a controlled way. A detailed structural analysis is carried out in order to characterize the induced defects and their concentration. The magnetometry revealed the coexistence of a paramagnetic and a ferromagnetic phase at room temperature in straight correlation with the structural properties. The saturation magnetization is found to increase with the intensification of the heat treatment, and, therefore, with the increase of the density of induced defects. The magnetic behavior is fully explained in terms of the bound magnetic polaron model. Based on the experimental findings, supported by theoretical calculations, we attribute the origin of the observed defect-induced-ferromagnetism to the ferromagnetic coupling between the Co ions mediated by magnetic polarons due to zinc interstitial defects. (C) 2020 Elsevier B.V. All rights reserved.

【 授权许可】

Free