| Non-stoichiometry-induced metal-to-insulator transition in nickelate thin films grown by pulsed laser deposition | |||||
| 작성자 | 김** | 작성일 | 2019-07-29 | 조회수 | 127 |
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Journal Article published Dec 2018 in Current Applied Physics volume 18 issue 12 on pages 1577 to 1582
Research funded by National Research Foundation of Korea (2017R1D1A1B030286142014R1A4A1071686) | Ministry of Education | Ministry of Science ICT and Future Planning | Basic Science Research Program (2016R1D1A1B03931748) | Creative Materials Discovery Program (2017M3D1A1040828)
AbstractWhile controlling the cation contents in perovskite rare-earth nickelate thin films, a metal-to-insulator phase transition is reported. Systematic control of cation stoichiometry has been achieved by manipulating the irradiation of excimer laser in pulsed laser deposition. Two rare-earth nickelate bilayer thin-film heterostructures with the controlled cation stoichiometry (i.e. stoichiometric and Ni-excessive) have been fabricated. It is found that the Ni-excessive nickelate film is structurally less dense than the stoichiometric film, albeit both of them are epitaxial and coherent with respect to the underlying substrate. More interestingly, as a temperature decreases, a metal-to-insulator transition is only observed in the Ni-excessive nickelate films, which can be associated with the enhanced disproportionation of the Ni charge valence. Based on our theoretical results, possible origins (e.g. anti-site defects) of the low-temperature insulating state are discussed with the need of future work for deeper understanding. Our work can be utilized to realize unusual physical phenomena (e.g. metal-to-insulator phase transitions) in complex oxide films by manipulating the chemical stoichiometry in pulsed laser deposition. |
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