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Engineering covalently bonded 2D layered materials by self-intercalation


Two-dimensional (2D) materials1,2,3,4,5 offer a unique platform from which to explore the physics of topology and many-body phenomena. New properties can be generated by filling the van der Waals gap of 2D materials with intercalants6,7; however, post-growth intercalation has usually been limited to alkali metals8,9,10. Here we show that the self-intercalation of native atoms11,12 into bilayer transition metal dichalcogenides during growth generates a class of ultrathin, covalently bonded materials, which we name ic-2D. The stoichiometry of these materials is defined by periodic occupancy patterns of the octahedral vacancy sites in the van der Waals gap, and their properties can be tuned by varying the coverage and the spatial arrangement of the filled sites7,13. By performing growth under high metal chemical potential14,15 we can access a range of tantalum-intercalated TaS(Se)y, including 25% Ta-intercalated Ta9S16, 33.3% Ta-intercalated Ta7S12, 50% Ta-intercalated Ta10S16, 66.7% Ta-intercalated Ta8Se12 (which forms a Kagome lattice) and 100% Ta-intercalated Ta9Se12. Ferromagnetic order was detected in some of these intercalated phases. We also demonstrate that self-intercalated V11S16, In11Se16 and FexTey can be grown under metal-rich conditions. Our work establishes self-intercalation as an approach through which to grow a new class of 2D materials with stoichiometry- or composition-dependent properties.

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Fig. 1: Self-intercalation in TaS2 crystals.
Fig. 2: Compositional engineering of TaxSy and TaxSey with different concentrations of intercalated Ta.
Fig. 3: Ferromagnetism in Ta-intercalated Ta7S12 ic-2D crystals.
Fig. 4: A library of ic-2D crystals.

Data availability

The main data supporting the findings of this study are available within the paper and its Supplementary Information. Additional data are available from the corresponding authors upon reasonable request.

Code availability

The Python code is available in the Supplementary Information.


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K.P.L. thanks A*STAR Project ‘Scalable Growth of Ultrathin Ferroelectric Materials for Memory Technologies’ (grant number A1983c0035) and support from the Centre for Advanced 2D Materials, National University of Singapore. W.Z. acknowledges support from the National Key R&D Program of China (2018YFA0305800) and the Natural Science Foundation of China (51622211). S.J.P. is grateful to the National University of Singapore for funding and the Ministry of Education (MOE) for a Tier 2 grant ‘Atomic scale understanding and optimization of defects in 2D materials’ (MOE2017-T2-2-139). Z.L. thanks the MOE for a Tier 2 grant (2017-T2-2-136) and a Tier 3 grant (2018-T3-1-002), and the A*STAR QTE programme. X.L. acknowledges support from the National Natural Science Foundation of China (grant number 11804286) and the Fundamental Research Funds for the Central Universities (grant number 19lgpy263). DFT calculations were performed using resources of the National Supercomputer Center in Guangzhou supported by the Special Program for Applied Research on Super Computation of the NSFC Guangdong Joint Fund (second phase). K.S.T. acknowledges funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant number 773122, LIMA). The Center for Nanostructured Graphene is sponsored by the Danish National Research Foundation, project DNRF103. We thank J. P. Shi, F. F. Cui and Y. F. Zhang for providing high-quality CVD samples.

Author information

Authors and Affiliations



X.Z., S.J.P. and K.P.L. conceived the idea. S.J.P. and K.P.L. supervised the execution of the whole work. X.Z. and W.Z. performed the electron microscopy experiments and data analysis. X.L., A.C.R.-J. and C.W. performed the DFT calculations and data analysis. A.C.R.-J. and K.S.T. performed the high-throughput DFT calculations. W.F., Y.D., L.K. and Z.L. grew the samples. D.W. and T.V. measured the magnetism. P.S. performed device fabrication and measurement. J.D. and S.N. developed the Python scripts for data analysis. All authors discussed the results and participated in writing the manuscript.

Corresponding authors

Correspondence to Xin Luo, Stephen J. Pennycook or Kian Ping Loh.

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The authors declare no competing interests.

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Peer review information Nature thanks Thomas Heine and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

This file contains Supplementary Text and Data, including Supplementary Figures 1-41, Supplementary Tables 1-3 and Supplementary References.

Supplementary Data

This file contains the Phython Code.

Video 1: Migration dynamics of intercalated Ta atoms.

The migration paths of intercalated Ta atoms were in situ tracked by sequential STEM imaging under the e-beam irradiation.

Video 2: Migration dynamics of surface Ta atoms.

The migration paths of intercalated Ta atoms were in situ tracked by sequential STEM imaging under the e-beam irradiation. The mobility of surface Ta atoms are much higher than that of intercalated Ta atoms.

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Zhao, X., Song, P., Wang, C. et al. Engineering covalently bonded 2D layered materials by self-intercalation. Nature 581, 171–177 (2020).

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