Atomic disorders in layer structured topological insulator SnBi2Te4 nanoplates
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Identification of atomic disorders and their subsequent control has proven to be a key issue in predicting, understanding, and enhancing the properties of newly emerging topological insulator materials. Here, we demonstrate direct evidence of the cation antisites in single-crystal SnBi2Te4 nanoplates grown by chemical vapor deposition, through a combination of sub-ångström-resolution imaging, quantitative image simulations, and density functional theory calculations. The results of these combined techniques revealed a recognizable amount of cation antisites between Bi and Sn, and energetic calculations revealed that such cation antisites have a low formation energy. The impact of the cation antisites was also investigated by electronic structure calculations together with transport measurement. The topological surface properties of the nanoplates were further probed by angle-dependent magnetotransport, and from the results, we observed a two-dimensional weak antilocalization effect associated with surface carriers. Our approach provides a pathway to identify the antisite defects in ternary chalcogenides and the application potential of SnBi2Te4 nanostructures in next-generation electronic and spintronic devices.
Keywordsmetal chalcogenide antisite defect nanoplate scanning transmission electron microscopy magnetotransport
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This work was financially supported by the Australian Research Council. Yichao Zou acknowledges the China Scholarship Council for providing her PhD stipend and the Graduate School of University of Queensland for providing the international travel award. Fantai Kong and Kyeongjae Cho were supported by Nano Material Technology Development Program (No. 2012M3A7B4049888) through the National Research Foundation of Korea (NRF) from the Ministry of Science, ICT and Future Planning, and Priority Research Center Program (No. 2010-0020207) through NRF from the Ministry of Education. The Australian Microscopy & Microanalysis Research Facility is acknowledged for providing characterization facilities.
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