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RISS 인기검색어
- 검색키워드
- 저자 : M. Subramanain (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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X-ray Absorption and Emission Studies of Mn-doped ZnO Thin Films
P. Thakur,S. Gautam,K. H. Chae,M. Subramanain,R. Jayavel,K. Asokan 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
The electronic structure of Mn-doped ZnO thin films, a dilute magnetic semiconductor (DMS) having possible room temperature (RT) ferromagnetism, synthesized with nominal compositions of Zn1−xMnxO (x = 0.03, 0.05, 0.07, 0.10, and 0.15) by using the spray pyrolysis method are investigated using soft X-ray absorption and emission spectroscopy. The intensity of the pre-edge spectral feature at the O K-edge increases with Mn concentration, which clearly reveals that there is a strong hybridization of Mn ions with the ZnO matrix. The near-edge X-ray absorption fine structure (NEXAFS) measurements at the Mn K- and L3,2-edges show a mixed valence nature for the Mn ions, with Mn2+ and Mn3+/Mn4+ states, and the Mn3+/Mn4+ states are observed to increase with the Mn-concentration. Mn L2,3 resonant inelastic X-ray scattering (RIXS) measurements show that the excess Mn interstitials appear in the sample and that direct exchange interactions with substitutional Mn atoms may explain the magnetic interaction in Mn-doped ZnO. The electronic structure of Mn-doped ZnO thin films, a dilute magnetic semiconductor (DMS) having possible room temperature (RT) ferromagnetism, synthesized with nominal compositions of Zn1−xMnxO (x = 0.03, 0.05, 0.07, 0.10, and 0.15) by using the spray pyrolysis method are investigated using soft X-ray absorption and emission spectroscopy. The intensity of the pre-edge spectral feature at the O K-edge increases with Mn concentration, which clearly reveals that there is a strong hybridization of Mn ions with the ZnO matrix. The near-edge X-ray absorption fine structure (NEXAFS) measurements at the Mn K- and L3,2-edges show a mixed valence nature for the Mn ions, with Mn2+ and Mn3+/Mn4+ states, and the Mn3+/Mn4+ states are observed to increase with the Mn-concentration. Mn L2,3 resonant inelastic X-ray scattering (RIXS) measurements show that the excess Mn interstitials appear in the sample and that direct exchange interactions with substitutional Mn atoms may explain the magnetic interaction in Mn-doped ZnO.
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Electronic Structure of Mn-Doped ZnO Studied by Using X-ray Absorption Spectroscopy
P. Thakur,K. H. Chae,M. Subramanain,R. Jayavel,K. Asokan 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Mn-doped ZnO thin films that showed ferromagnetism at room temperature were synthesized with nominal compositions Zn1-xMnxO (x = 0.03, 0.05, 0.07, 0.10 and 0.15) by using a spray pyrolysis technique. High-resolution X-ray diffraction studies suggested that the doped Mn ions occupied Zn sites and that all the samples exhibited a wurtzite hexagonal-like crystal structure similar to that of the parent compound, ZnO. The near-edge X-ray absorption fine structure (NEXAFS) measurements at the O K-edge clearly exhibited a pre-edge spectral feature, which evolved with Mn doping, similar to one observed in hole-doped cuprates and manganites. The Mn L3;2-edge NEXAFS spectra exhibited divalent Mn apart from mixed valent Mn3+ / Mn4+ states, which were well supported by Mn K-edge spectra.
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Electronic Structure of Co-doped ZnO Thin Films by X-ray Absorption and Emission Spectroscopy
S. Gautam,P. Thakur,K. H. Chae,G. S. Chang,M. Subramanain,R. Jayavel,K. Asokan 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
The electronic structure of Co-doped ZnO thin films, synthesized with a nominal composition of Zn1−xCoxO (x = 0.03, 0.05, 0.7, 0.10, and 0.15) by using spray pyrolysis method, has been investigated using near edge X-ray absorption fine structure (NEXAFS) measurements at the O K- and the Co L3,2-edges and using resonant inelastic X-ray scattering (RIXS) measurements at Co L3,2-edge. All the prepared Zn1−xCoxO thin films showed ferromagnetic behavior at room temperature, as measured by using an alternating gradient force magnetometer (AGFM). The intensity of the pre-edge spectral feature at the O K-edge increases with the Co concentration, which clearly reveals that there is strong hybridization of O 2p − Co 3d atoms in the ZnO matrix. Spectral features of the Co L3,2-edge NEXAFS exhibit multiple absorption peaks and are similar to those of Co2+ ions coordinated in tetrahedral symmetry by four oxygen atoms. These results clearly demonstrate that Co is in a 2+ state, substituting at the Zn site. Co L3,2-edge RIXS measurements show that the substitution by Co atoms can explain the magnetic interaction in Co-doped ZnO. The electronic structure of Co-doped ZnO thin films, synthesized with a nominal composition of Zn1−xCoxO (x = 0.03, 0.05, 0.7, 0.10, and 0.15) by using spray pyrolysis method, has been investigated using near edge X-ray absorption fine structure (NEXAFS) measurements at the O K- and the Co L3,2-edges and using resonant inelastic X-ray scattering (RIXS) measurements at Co L3,2-edge. All the prepared Zn1−xCoxO thin films showed ferromagnetic behavior at room temperature, as measured by using an alternating gradient force magnetometer (AGFM). The intensity of the pre-edge spectral feature at the O K-edge increases with the Co concentration, which clearly reveals that there is strong hybridization of O 2p − Co 3d atoms in the ZnO matrix. Spectral features of the Co L3,2-edge NEXAFS exhibit multiple absorption peaks and are similar to those of Co2+ ions coordinated in tetrahedral symmetry by four oxygen atoms. These results clearly demonstrate that Co is in a 2+ state, substituting at the Zn site. Co L3,2-edge RIXS measurements show that the substitution by Co atoms can explain the magnetic interaction in Co-doped ZnO.
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