Journal
ACS NANO
Volume 14, Issue 9, Pages 11262-11272Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.0c03149
Keywords
surface reconstruction; MnBi2Te4; magnetic topological insulator; antisite defects; tellurium vacancy; in situ surface dynamics
Categories
Funding
- National Natural Science Foundation of China [11974156, 11874195, 11674149, 11674150]
- Guangdong International Science Collaboration Project [2019A050510001, 2017ZT07C062]
- National Key Research and Development Program [2019YFA0704901]
- Guangdong Provincial Key Laboratory of Computational Science and Material Design [2019B030301001]
- Key-Area Research and Development Program of Guangdong Province [2019B010931001]
- Guangdong Innovative and Entrepreneurial Research Team Program [2017ZT07C062, 2016ZT06D348, 2019ZT08C044]
- Highlight Project of the College of Science, SUSTech. [PHYS-HL-20201]
- Science, Technology and Innovation Commission of Shenzhen Municipality [ZDSYS20190902092905285, KQTD20190929173815000]
- Presidential Fund and Development and Reform Commission of Shenzhen Municipality
- Center for Computational Science and Engineering at SUSTech
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MnBi2Te4 is an antiferromagnetic topological insulator that has stimulated intense interest due to its exotic quantum phenomena and promising device applications. The surface structure is a determinant factor to understand the magnetic and topological behavior of MnBi2Te4, yet its precise atomic structure remains elusive. Here we discovered a surface collapse and reconstruction of few-layer MnBi2Te4 exfoliated under delicate protection. Instead of the ideal septuple-layer structure in the bulk, the collapsed surface is shown to reconstruct as a Mn-doped Bi2Te3 quintuple layer and a MnxBiyTe double layer with a clear van der Waals gap in between. Combined with first-principles calculations, such surface collapse is attributed to the abundant intrinsic Mn-Bi antisite defects and the tellurium vacancy in the exfoliated surface, which is further supported by in situ annealing and electron irradiation experiments. Our results shed light on the understanding of the intricate surface-bulk correspondence of MnBi2Te4 and provide an insightful perspective on the surface-related quantum measurements in MnBi2Te4 few-layer devices.
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