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Corrigendum to “Defect-induced reversible ferromagnetism in hydrogenated ZnO:Co” [J. Magn. Magn. Mater. 322 (2010) 2187]
Journal of Magnetism and Magnetic Materials ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Erratum
Erratum to “Defect-induced reversible ferromagnetism in hydrogenated ZnO:Co” [J. Magn. Magn. Mater. 322 (2010) 2187] R.K. Singhal a,n, A. Samariya b, S. Kumar b, Y.T. Xing c, U.P. Deshpande d, T. Shripathi d, E. Saitovitch c a
Department of Physics, University of Rajasthan, Jaipur 302004, India Department of Physics, M.L. Sukhadia University, Udaipur 313002, India c CBPF, Rua Dr. Xavier Sigaud 150, Urca, Rio de Janeiro, Brazil d UGC-DAE CSR, University Campus, Indore 452001, India b
The present Erratum is in regard of Fig. 2 displaying the Co 2p XPS spectra for the Co doped ZnO samples in this article. The concern is that the background features look identical in these Co 2p spectra despite a clear shift observed in the spectrum of hydrogenated sample. This should not have been so. To resolve this problem we recovered and looked at the raw data for these samples (the as-prepared sample Zn0.95Co0.05O and the hydrogenated sample Zn0.95Co0.05O:H). It appears that the Co 2p spectra presented in the article had been mistreated due to a series of wrong processes during data analysis i.e., the normalization, background subtraction and smoothing processes. Through this Erratum, we want to replace Fig. 2 by the correct unprocessed figures, as described below. The full scan profile for the sample Zn0.95Co0.05O is displayed in Fig. 2a while Fig. 2b presents the raw untreated Co 2p XPS spectra for the above two samples (just after C 1s peak correction). Also the slightly modified text for the relevant Section 3.2 (Co 2p XPS data) is given below. 3.2. Co 2p XPS data Fig. 2a presents the full scan profile for sample Zn0.95Co0.05O. Fig. 2b compares the Co 2p XPS spectra of Zn0.95Co0.05O and Zn0.95Co0.05O: H. The peaks A1 and A3 correspond to Co 2p3/2 and Co 2p1/2 levels, respectively, while A2 and A4 correspond to their satellites [11,13]. To exactly locate peak positions, the Gaussian was fitted. Position of Co 2p3/2 peak A1 ( 780.2 eV) is found similar to CoO, specific to Co–O bonding ( 780.1 eV) [11,14] and much different from Co metal ( 778 eV) and Co2O3 ( 779 eV). Also the difference between Co 2p3/2 and Co 2p1/2 ( 15.3 eV) is close to the value of CoO 15.2 eV [11,14]. Intensity of the satellite peak (at 787.0 eV) is nearly half of Co 2p3/2. These findings confirm that Co ions stay bivalent in ZnO lattice [15] having a high-spin d state [16], without forming impurity phases like metallic Co or Co2O3. However, the Co 2p3/2 signal in Zn0.95Co0.05O:H is shifted to higher energy by 0.9 eV than Zn0.95Co0.05O. When Co ions bind to H the binding energy is known to increase by 1 eV [14]. Thus our findings clearly point out that H-doping affects Co–O bonding states in ZnCoO lattice and binds to Co. Importantly, unlike Lee et al. [11] who noticed two additional peaks, ascribed to H-induced precipitation of Co metal, we did not notice any such structures. In addition, the pellets were fractured in-situ to obtain a new surface emerged from bulk. This was done a couple of times. The purpose was to carefully check whether there were any signs of metallic Co from bulk. However, this weighed against our fear as the spectra showed no additional features to be assigned to metallic Co, unlike in Ref. [11]. Thus the possibility of metallic Co in our samples can be ruled out.
n
DOI of original article: http://dx.doi.org/10.1016/j.jmmm.2010.02.007 Corresponding author. Tel.: þ 91 141 2545931; fax: þ91 141 2701038. E-mail address: [email protected] (R.K. Singhal).
http://dx.doi.org/10.1016/j.jmmm.2014.04.072 0304-8853/& 2014 Elsevier B.V. All rights reserved.
Please cite this article as: R.K. Singhal, et al., Journal of Magnetism and Magnetic Materials (2014), http://dx.doi.org/10.1016/j. jmmm.2014.04.072i
2
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R.K. Singhal et al. / Journal of Magnetism and Magnetic Materials ∎ (∎∎∎∎) ∎∎∎–∎∎∎
Fig. 2. (a) The full scan XPS profile for Zn0.95Co0.05O and (b) comparison of Co 2p XPS spectra for Zn0.95Co0.05O and Zn0.95Co0.05O:H.
Please cite this article as: R.K. Singhal, et al., Journal of Magnetism and Magnetic Materials (2014), http://dx.doi.org/10.1016/j. jmmm.2014.04.072i
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Q1 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 Q2 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
Contents lists available at ScienceDirect
Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm
Erratum
Erratum to “Defect-induced reversible ferromagnetism in hydrogenated ZnO:Co” [J. Magn. Magn. Mater. 322 (2010) 2187] R.K. Singhal a,n, A. Samariya b, S. Kumar b, Y.T. Xing c, U.P. Deshpande d, T. Shripathi d, E. Saitovitch c a
Department of Physics, University of Rajasthan, Jaipur 302004, India Department of Physics, M.L. Sukhadia University, Udaipur 313002, India c CBPF, Rua Dr. Xavier Sigaud 150, Urca, Rio de Janeiro, Brazil d UGC-DAE CSR, University Campus, Indore 452001, India b
The present Erratum is in regard of Fig. 2 displaying the Co 2p XPS spectra for the Co doped ZnO samples in this article. The concern is that the background features look identical in these Co 2p spectra despite a clear shift observed in the spectrum of hydrogenated sample. This should not have been so. To resolve this problem we recovered and looked at the raw data for these samples (the as-prepared sample Zn0.95Co0.05O and the hydrogenated sample Zn0.95Co0.05O:H). It appears that the Co 2p spectra presented in the article had been mistreated due to a series of wrong processes during data analysis i.e., the normalization, background subtraction and smoothing processes. Through this Erratum, we want to replace Fig. 2 by the correct unprocessed figures, as described below. The full scan profile for the sample Zn0.95Co0.05O is displayed in Fig. 2a while Fig. 2b presents the raw untreated Co 2p XPS spectra for the above two samples (just after C 1s peak correction). Also the slightly modified text for the relevant Section 3.2 (Co 2p XPS data) is given below. 3.2. Co 2p XPS data Fig. 2a presents the full scan profile for sample Zn0.95Co0.05O. Fig. 2b compares the Co 2p XPS spectra of Zn0.95Co0.05O and Zn0.95Co0.05O: H. The peaks A1 and A3 correspond to Co 2p3/2 and Co 2p1/2 levels, respectively, while A2 and A4 correspond to their satellites [11,13]. To exactly locate peak positions, the Gaussian was fitted. Position of Co 2p3/2 peak A1 ( 780.2 eV) is found similar to CoO, specific to Co–O bonding ( 780.1 eV) [11,14] and much different from Co metal ( 778 eV) and Co2O3 ( 779 eV). Also the difference between Co 2p3/2 and Co 2p1/2 ( 15.3 eV) is close to the value of CoO 15.2 eV [11,14]. Intensity of the satellite peak (at 787.0 eV) is nearly half of Co 2p3/2. These findings confirm that Co ions stay bivalent in ZnO lattice [15] having a high-spin d state [16], without forming impurity phases like metallic Co or Co2O3. However, the Co 2p3/2 signal in Zn0.95Co0.05O:H is shifted to higher energy by 0.9 eV than Zn0.95Co0.05O. When Co ions bind to H the binding energy is known to increase by 1 eV [14]. Thus our findings clearly point out that H-doping affects Co–O bonding states in ZnCoO lattice and binds to Co. Importantly, unlike Lee et al. [11] who noticed two additional peaks, ascribed to H-induced precipitation of Co metal, we did not notice any such structures. In addition, the pellets were fractured in-situ to obtain a new surface emerged from bulk. This was done a couple of times. The purpose was to carefully check whether there were any signs of metallic Co from bulk. However, this weighed against our fear as the spectra showed no additional features to be assigned to metallic Co, unlike in Ref. [11]. Thus the possibility of metallic Co in our samples can be ruled out.
n
DOI of original article: http://dx.doi.org/10.1016/j.jmmm.2010.02.007 Corresponding author. Tel.: þ 91 141 2545931; fax: þ91 141 2701038. E-mail address: [email protected] (R.K. Singhal).
http://dx.doi.org/10.1016/j.jmmm.2014.04.072 0304-8853/& 2014 Elsevier B.V. All rights reserved.
Please cite this article as: R.K. Singhal, et al., Journal of Magnetism and Magnetic Materials (2014), http://dx.doi.org/10.1016/j. jmmm.2014.04.072i
2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
R.K. Singhal et al. / Journal of Magnetism and Magnetic Materials ∎ (∎∎∎∎) ∎∎∎–∎∎∎
Fig. 2. (a) The full scan XPS profile for Zn0.95Co0.05O and (b) comparison of Co 2p XPS spectra for Zn0.95Co0.05O and Zn0.95Co0.05O:H.
Please cite this article as: R.K. Singhal, et al., Journal of Magnetism and Magnetic Materials (2014), http://dx.doi.org/10.1016/j. jmmm.2014.04.072i