Supporting Information Co-rich ZnCoO nanoparticles embedded in ...
Supporting Information
Co-rich ZnCoO nanoparticles embedded in wurtzite Zn1-xCoxO thin films: possible origin of superconductivity
Yu-Jia Zeng,*,† ‡§ Nicolas Gauquelin,# Dan-Ying Li,‡ Shuang-Chen Ruan,† Hai-Ping He,§ Ricardo Egoavil,# Zhi-Zhen Ye,§Johan Verbeeck,# Joke Hadermann,# Margriet J. Van Bael,‡ and Chris Van Haesendonck,*,‡
†
Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering,
Shenzhen University, Shenzhen, 518060, P. R. China. ‡
Solid State Physics and Magnetism Section, KU Leuven, Celestijnenlaan 200 D, BE-3001
Leuven, Belgium #
Electron Microscopy for Materials Science – EMAT, University of Antwerp,
Groenenborgerlaan 171 BE-2020 Antwerp, Belgium §
State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering,
Zhejiang University, Hangzhou 310027, P. R. China
S-1
* [email protected]; [email protected]
Figure S1. A typical electron diffraction pattern of the Zn1-xCoxO matrix grown on a Si substrate. The pattern can be indexed using the wurtzite structure.
Figure S2. An electron diffraction pattern of the Zn1-xCoxO film grown on a Si substrate acquired from an area containing a misaligned grain. The sample is oriented in such a way that the [100] zone axis of the misaligned grain is parallel to the electron beam. Positions of the reflections attributed to the grain are highlighted with a grid.
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Figure S3. EFTEM maps of the elemental distribution in the Zn1-xCoxO thin film deposited on a Si substrate. The misaligned grains are marked with asterisks. Co-rich nanoparticles can be found at different locations.
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Figure S4. EFTEM maps of the elemental distribution in the Zn1-xCoxO thin film deposited on a SiO2 substrate. Co is evenly distributed and no Co-rich nanoparticles are observed.
Figure S5. Raw Co L2,3 EELS map from which the spectra for compositional analysis were extracted. The brighter region corresponds to a precipitate (see main text). The areas are color coded as follows: matrix in blue (5x4 pixels), center of the precipitate in red (2x2 pixels) and edge of the precipitate in green (2x2 pixels). S-6
Table S1. Crystal field and charge transfer parameters used for the multiplet simulations performed with the CTM4XAS 5.5 software (Stavitski & de Groot, Micron, 2010, 41, 687). For all simulations, the Slater integrals Fdd, Fpd and Gpd were set to 1; the spin-orbit coupling was kept at 98%. According to the experimental resolution and the life-time broadening, the simulations were convolved with a Gaussian of G= 0.25eV and with a Lorentzian with L3= 0.25eV and L2= 0.8eV for the L3 and L2 edges, respectively. For Co2+ Oh, Co2+ Td and Co3+ Oh values reported by Morales et al. ( J. Phys. Chem. B, 2004, 108, 16201) were used, for Co3+ D4h, values reported by Merz et al.( Phys. Rev. B 2012, 86,104503) were used, for Co3+ D3d and Co4+ D3d values reported by Lin et al. ( Phys. Rev. B, 2010, 81, 115138) were used and finally for Co4+ Td values reported by Kroll et al. (Phys. Rev. B, 2006, 74, 115124) were used. Crystal Field
Charge Transfer
Valence Symmetry
Co
Dt
Ds
Udd
Upd
Oh
0.6
0
0
7
0
2
2
1
2
1
Td
0.25
0
0
7
0
2
0.8
1.6
0.8
1.6
D3d
1.9
0.2
0.5
4
5
6
3.5
7
3.5
7
D4h
0.6
0.2
0.5
7
0
2
0.8
1.6
0.8
1.6
Oh
1.9
0
0
4.5
0
2
2
1
2
1
D3d
4
0.2
0.5
Td
1.2
0
0
3.5
7
T(b1) T(b2) T(a1)
T(e)
2+
Co3+
Co
10 Dq
No Charge Transfer terms
4+
-1.1
S-7
4.5
6
3.5
7
Table S2. Average results of the fits performed in the regions presented in figure 5. An upper limit for the error bars on the average weights of each component is estimated from the maximum of the experimental standard deviation within a group (matrix/precipitate/edge) divided by the square root of the population size. Values in % matrix center precipitate edge precipitate
Co2+ Oh
Co2+ Td
Co3+ D3d
Co3+ D4h
Co3+ Oh
Co4+ D3d
Co4+ Td
2.0 ± 1.1
85.3 ± 1.1
2.0 ± 1.1
0.4 ± 1.1
10.2 ± 1.1
0.1 ± 1.1
0.0 ± 1.1
Oxidation state 2.13
38.5 ± 2.3
0.0 ± 2.3
12.4 ± 2.3
0.2 ± 2.3
48.8 ± 2.3
0.1 ± 2.3
0.0 ± 2.3
2.62
18.5 ± 2.3
0.0 ± 2.3
14.5 ± 2.3
0.0 ± 2.3
67.0 ± 2.3
0.0 ± 2.3
0.0 ± 2.3
2.82
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1.60
(a)
1.50
-5
M (10 emu)
1.55
1.45 1.40 1.35 0
5
10
15
20
Temperature (K)
1.60 1.55 1.50
-5
M (10 emu)
(b)
1.45 1.40 1.35 0.0
0.1
0.2
0.3
0.4
0.5
1/T (1/K)
Figure S6. Superconducting properties of the Zn1-xCoxO thin film grown on a Si substrate. (a) Temperature dependence of the magnetization measured at a magnetic field of 0.1 T in a zero-field cooling process. (b) Magnetization as a function of 1/T.
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Co-rich ZnCoO nanoparticles embedded in wurtzite Zn1-xCoxO thin films: possible origin of superconductivity
Yu-Jia Zeng,*,† ‡§ Nicolas Gauquelin,# Dan-Ying Li,‡ Shuang-Chen Ruan,† Hai-Ping He,§ Ricardo Egoavil,# Zhi-Zhen Ye,§Johan Verbeeck,# Joke Hadermann,# Margriet J. Van Bael,‡ and Chris Van Haesendonck,*,‡
†
Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering,
Shenzhen University, Shenzhen, 518060, P. R. China. ‡
Solid State Physics and Magnetism Section, KU Leuven, Celestijnenlaan 200 D, BE-3001
Leuven, Belgium #
Electron Microscopy for Materials Science – EMAT, University of Antwerp,
Groenenborgerlaan 171 BE-2020 Antwerp, Belgium §
State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering,
Zhejiang University, Hangzhou 310027, P. R. China
S-1
* [email protected]; [email protected]
Figure S1. A typical electron diffraction pattern of the Zn1-xCoxO matrix grown on a Si substrate. The pattern can be indexed using the wurtzite structure.
Figure S2. An electron diffraction pattern of the Zn1-xCoxO film grown on a Si substrate acquired from an area containing a misaligned grain. The sample is oriented in such a way that the [100] zone axis of the misaligned grain is parallel to the electron beam. Positions of the reflections attributed to the grain are highlighted with a grid.
S-2
S-3
Figure S3. EFTEM maps of the elemental distribution in the Zn1-xCoxO thin film deposited on a Si substrate. The misaligned grains are marked with asterisks. Co-rich nanoparticles can be found at different locations.
S-4
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Figure S4. EFTEM maps of the elemental distribution in the Zn1-xCoxO thin film deposited on a SiO2 substrate. Co is evenly distributed and no Co-rich nanoparticles are observed.
Figure S5. Raw Co L2,3 EELS map from which the spectra for compositional analysis were extracted. The brighter region corresponds to a precipitate (see main text). The areas are color coded as follows: matrix in blue (5x4 pixels), center of the precipitate in red (2x2 pixels) and edge of the precipitate in green (2x2 pixels). S-6
Table S1. Crystal field and charge transfer parameters used for the multiplet simulations performed with the CTM4XAS 5.5 software (Stavitski & de Groot, Micron, 2010, 41, 687). For all simulations, the Slater integrals Fdd, Fpd and Gpd were set to 1; the spin-orbit coupling was kept at 98%. According to the experimental resolution and the life-time broadening, the simulations were convolved with a Gaussian of G= 0.25eV and with a Lorentzian with L3= 0.25eV and L2= 0.8eV for the L3 and L2 edges, respectively. For Co2+ Oh, Co2+ Td and Co3+ Oh values reported by Morales et al. ( J. Phys. Chem. B, 2004, 108, 16201) were used, for Co3+ D4h, values reported by Merz et al.( Phys. Rev. B 2012, 86,104503) were used, for Co3+ D3d and Co4+ D3d values reported by Lin et al. ( Phys. Rev. B, 2010, 81, 115138) were used and finally for Co4+ Td values reported by Kroll et al. (Phys. Rev. B, 2006, 74, 115124) were used. Crystal Field
Charge Transfer
Valence Symmetry
Co
Dt
Ds
Udd
Upd
Oh
0.6
0
0
7
0
2
2
1
2
1
Td
0.25
0
0
7
0
2
0.8
1.6
0.8
1.6
D3d
1.9
0.2
0.5
4
5
6
3.5
7
3.5
7
D4h
0.6
0.2
0.5
7
0
2
0.8
1.6
0.8
1.6
Oh
1.9
0
0
4.5
0
2
2
1
2
1
D3d
4
0.2
0.5
Td
1.2
0
0
3.5
7
T(b1) T(b2) T(a1)
T(e)
2+
Co3+
Co
10 Dq
No Charge Transfer terms
4+
-1.1
S-7
4.5
6
3.5
7
Table S2. Average results of the fits performed in the regions presented in figure 5. An upper limit for the error bars on the average weights of each component is estimated from the maximum of the experimental standard deviation within a group (matrix/precipitate/edge) divided by the square root of the population size. Values in % matrix center precipitate edge precipitate
Co2+ Oh
Co2+ Td
Co3+ D3d
Co3+ D4h
Co3+ Oh
Co4+ D3d
Co4+ Td
2.0 ± 1.1
85.3 ± 1.1
2.0 ± 1.1
0.4 ± 1.1
10.2 ± 1.1
0.1 ± 1.1
0.0 ± 1.1
Oxidation state 2.13
38.5 ± 2.3
0.0 ± 2.3
12.4 ± 2.3
0.2 ± 2.3
48.8 ± 2.3
0.1 ± 2.3
0.0 ± 2.3
2.62
18.5 ± 2.3
0.0 ± 2.3
14.5 ± 2.3
0.0 ± 2.3
67.0 ± 2.3
0.0 ± 2.3
0.0 ± 2.3
2.82
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1.60
(a)
1.50
-5
M (10 emu)
1.55
1.45 1.40 1.35 0
5
10
15
20
Temperature (K)
1.60 1.55 1.50
-5
M (10 emu)
(b)
1.45 1.40 1.35 0.0
0.1
0.2
0.3
0.4
0.5
1/T (1/K)
Figure S6. Superconducting properties of the Zn1-xCoxO thin film grown on a Si substrate. (a) Temperature dependence of the magnetization measured at a magnetic field of 0.1 T in a zero-field cooling process. (b) Magnetization as a function of 1/T.
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