Enhanced defect-mediated ferromagnetism in Cu2O by Co doping

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:441

Article

Brandt, Iuri S.^1,2  Tumelero, Milton A.^1,3  Lima, Enio, Jr.^4,5  da Silva, Douglas L.⁶  Zysler, Roberto D.^4,5  Faccio, Ricardo⁷  Pasa, Andre A.¹ 

[1] Univ Fed Santa Catarina, Dept Fis, BR-88040900 Florianopolis, SC, Brazil

[2] Univ Fed Santa Catarina, Dept Engn Mecan, Programa Posgrad Ciencia & Engn Mat, BR-88040900 Florianopolis, SC, Brazil

[3] Univ Fed Rio Grande do Sul, Inst Fis, BR-91501970 Porto Alegre, RS, Brazil

[4] Ctr Atom Bariloche, RA-8400 San Carlos De Bariloche, Argentina

[5] Inst Balseiro, RA-8400 San Carlos De Bariloche, Argentina

[6] Univ Fed Pelotas, Dept Fis, BR-96010900 Pelotas, Brazil

[7] Univ Republica, DETEMA, Fac Quim, CentroNanoMat CryssMat, Montevideo 11800, Uruguay

关键词: Electrodeposition;    Cuprous oxide;    Ferromagnetism;    Point defects;    DFT;   

DOI  :  10.1016/j.jmmm.2017.05.057

来源: Elsevier

【 摘 要 】

In this work an extensive characterization of Co doped Cu2O thin films grown by electrochemical deposition is presented. The doped films showed ferromagnetic behavior, with impressive Curie temperature up to 700 K. Undoped samples also presented magnetic moments at room temperature, but much reduced when compared to doped ones. The observed magnetism in undoped and doped samples was taken as an indicative of a defect-mediated ferromagnetism. Moreover, the sample magnetization was reduced as a consequence of a decreasing in defect density due to thermal annealing. Polarizationdependent X-ray absorption measurements demonstrated that oxygen derived states are the source of the observed magnetic moment and its magnetic dichroism depends on the amount of point defects. Structural, optical and electrical characterization provides information that confirms the incorporation of Co atoms in the Cu2O lattice, without the formation of secondary segregated Co phases. In addition, Electron Paramagnetic Resonance and Glow Discharge Optical Emission Spectroscopy measurements reject the existence of contaminants in the films, dismissing them as the source for the observed magnetism. Computational calculations have shown that Co doping shall locally increases the amount of defects, such as interstitial O, leading to highly oxidized regions from where the unpaired spin arises. This situation generates a picture similar to the magnetic polaron theory, but with the dopant ion pinning the defects. (C) 2017 Elsevier B. V. All rights reserved.

【 授权许可】

Free