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https://doi.org/10.1063/1.3581046
Title: | Surface ferromagnetism in hydrogenated-ZnO film | Authors: | Li, T. Ong, C.S. Herng, T.S. Yi, J.B. Bao, N.N. Xue, J.M. Feng, Y.P. Ding, J. |
Issue Date: | 11-Apr-2011 | Citation: | Li, T., Ong, C.S., Herng, T.S., Yi, J.B., Bao, N.N., Xue, J.M., Feng, Y.P., Ding, J. (2011-04-11). Surface ferromagnetism in hydrogenated-ZnO film. Applied Physics Letters 98 (15) : -. ScholarBank@NUS Repository. https://doi.org/10.1063/1.3581046 | Abstract: | Nonmagnetic ZnO films were found to exhibit room temperature ferromagnetism after hydrogen annealing at elevated temperatures (100-500°C), accompanied by (OH) bonds detection. The areal saturation magnetization Ms (∼1.1× 10-5 emu cm-2) was insensitive to film thickness, suggesting surface magnetism. The attribution to OH bonds on surface was further supported when the ferromagnetism disappeared after a short immersion for 1 s in acid solution while ferromagnetism was relatively stable in basic environment. The alternative H2 - and Ar-annealing can switch ferromagnetic "on" and "off" state, as the annealing under Ar atmosphere can reduce OH bond quantity significantly. First-principles calculations have further confirmed that OH-terminated ZnO surface belonging to the p31m two-dimensional space group has the lowest formation energy of -2.97 eV and a magnetic moment of 0.30 μB per OH due to unpaired magnetic moment of electrons occupying O 2p orbital. Insufficient surface OH concentration may result in antiferromagnetism and/or paramagnetism. © 2011 American Institute of Physics. | Source Title: | Applied Physics Letters | URI: | http://scholarbank.nus.edu.sg/handle/10635/86746 | ISSN: | 00036951 | DOI: | 10.1063/1.3581046 |
Appears in Collections: | Staff Publications |
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