Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Operando electron microscopy investigation of polar domain dynamics in twisted van der Waals homobilayers

Nature Materials volume 22, pages 992–998 (2023)Cite this article

Subjects

Abstract

Conventional antiferroelectric materials with atomic-scale anti-aligned dipoles undergo a transition to a ferroelectric (FE) phase under strong electric fields. The moiré superlattice formed in the twisted stacks of van der Waals crystals exhibits polar domains alternating in moiré length with anti-aligned dipoles. In this moiré domain antiferroelectic (MDAF) arrangement, the distribution of electric dipoles is distinguished from that of two-dimensional FEs, suggesting dissimilar domain dynamics. Here we performed an operando transmission electron microscopy investigation on twisted bilayer WSe2 to observe the polar domain dynamics in real time. We find that the topological protection, provided by the domain wall network, prevents the MDAF-to-FE transition. As one decreases the twist angle, however, this transition occurs as the domain wall network disappears. Exploiting stroboscopic operando transmission electron microscopy on the FE phase, we measure a maximum domain wall velocity of 300 μm s–1. Domain wall pinnings by various disorders limit the domain wall velocity and cause Barkhausen noises in the polarization hysteresis loop. Atomic-scale analysis of the pinning disorders provides structural insight on how to improve the switching speed of van der Waals FEs.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Operando TEM investigation of domain dynamics in twisted bilayer TMDs.
Fig. 2: MDAF-to-FE transition in twisted bilayer TMD.
Fig. 3: FE domain dynamics.

Similar content being viewed by others

Data availability

The data that support the findings of this study are presented in the paper, Extended Data and Supplementary Information. Any other relevant data are available from the corresponding authors upon request and also available at https://doi.org/10.5281/zenodo.7956290.

References

  1. Du, L. et al. Engineering symmetry breaking in 2D layered materials. Nat. Rev. Phys. 3, 193–206 (2021).

    Article  CAS  Google Scholar 

  2. Li, L. & Wu, M. Binary compound bilayer and multilayer with vertical polarizations: two-dimensional ferroelectrics, multiferroics, and nanogenerators. ACS Nano 11, 6382–6388 (2017).

    Article  CAS  Google Scholar 

  3. Sung, J. et al. Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe2/MoSe2 bilayers. Nat. Nanotechnol. 15, 750–754 (2020).

    Article  CAS  Google Scholar 

  4. Ferreira, F., Enaldiev, V. V., Fal’ko, V. I. & Magorrian, S. J. Weak ferroelectric charge transfer in layer-asymmetric bilayers of 2D semiconductors. Sci. Rep. 11, 13422 (2021).

    Article  CAS  Google Scholar 

  5. Woods, C. et al. Charge-polarized interfacial superlattices in marginally twisted hexagonal boron nitride. Nat. Commun. 12, 347 (2021).

    Article  CAS  Google Scholar 

  6. Yasuda, K., Wang, X., Watanabe, K., Taniguchi, T. & Jarillo-Herrero, P. Stacking-engineered ferroelectricity in bilayer boron nitride. Science 372, 1458–1462 (2021).

    Article  CAS  Google Scholar 

  7. Vizner Stern, M. et al. Interfacial ferroelectricity by van der Waals sliding. Science 372, 1462–1466 (2021).

    Article  CAS  Google Scholar 

  8. Liu, Y., Liu, S., Li, B., Yoo, W. J. & Hone, J. Identifying the transition order in an artificial ferroelectric van der Waals heterostructure. Nano Lett. 22, 1265–1269 (2022).

    Article  CAS  Google Scholar 

  9. Wang, X. et al. Interfacial ferroelectricity in rhombohedral-stacked bilayer transition metal dichalcogenides. Nat. Nanotechnol. 17, 367–371 (2022).

    Article  CAS  Google Scholar 

  10. Carr, S. et al. Relaxation and domain formation in incommensurate 2D heterostructures. Phys. Rev. B 98, 224102 (2018).

    Article  CAS  Google Scholar 

  11. Enaldiev, V., Zólyomi, V., Yelgel, C., Magorrian, S. & Fal’ko, V. Stacking domains and dislocation networks in marginally twisted bilayers of transition metal dichalcogenides. Phys. Rev. Lett. 124, 206101 (2020).

    Article  CAS  Google Scholar 

  12. Rosenberger, M. R. et al. Twist angle-dependent atomic reconstruction and moiré patterns in transition metal dichalcogenide heterostructures. ACS Nano 14, 4550–4558 (2020).

    Article  CAS  Google Scholar 

  13. Weston, A. et al. Interfacial ferroelectricity in marginally twisted 2D semiconductors. Nat. Nanotechnol. 17, 390–395 (2022).

    Article  CAS  Google Scholar 

  14. Weston, A. et al. Atomic reconstruction in twisted bilayers of transition metal dichalcogenides. Nat. Nanotechnol. 15, 592–597 (2020).

    Article  CAS  Google Scholar 

  15. Fei, Z. et al. Ferroelectric switching of a two-dimensional metal. Nature 560, 336–339 (2018).

    Article  CAS  Google Scholar 

  16. Liu, F. et al. Room-temperature ferroelectricity in CuInP2S6 ultrathin flakes. Nat. Commun. 7, 12357 (2016).

    Article  CAS  Google Scholar 

  17. Brown, L. et al. Twinning and twisting of tri- and bilayer graphene. Nano Lett. 12, 1609–1615 (2012).

    Article  CAS  Google Scholar 

  18. Yoo, H. et al. Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene. Nat. Mater. 18, 448–453 (2019).

    Article  CAS  Google Scholar 

  19. Kittel, C. Theory of antiferroelectric crystals. Phys. Rev. 82, 729–732 (1951).

    Article  CAS  Google Scholar 

  20. Randall, C. A., Fan, Z., Reaney, I., Chen, L. Q. & Trolier‐McKinstry, S. Antiferroelectrics: history, fundamentals, crystal chemistry, crystal structures, size effects, and applications. J. Am. Ceram. Soc. 104, 3775–3810 (2021).

    Article  CAS  Google Scholar 

  21. Huang, F.-T. & Cheong, S.-W. Aperiodic topological order in the domain configurations of functional materials. Nat. Rev. Mater. 2, 17004 (2017).

    Article  Google Scholar 

  22. Butz, B. et al. Dislocations in bilayer graphene. Nature 505, 533–537 (2014).

    Article  CAS  Google Scholar 

  23. Engelke, R. et al. Topological nature of dislocation networks in two-dimensional moiré materials. Phys. Rev. B 107, 125413 (2023).

    Article  CAS  Google Scholar 

  24. Rudyak, V. M. The Barkhausen effect. Sov. Phys. Usp. 13, 461–479 (1971).

    Article  Google Scholar 

  25. Shur, V. Y., Rumyantsev, E., Kuminov, V., Subbotin, A. & Kozhevnikov, V. Barkhausen effect in stepped motion of a plane domain boundary in gadolinium molybdate. Phys. Solid State 41, 269–273 (1999).

    Article  CAS  Google Scholar 

  26. Gruverman, A. et al. Direct studies of domain switching dynamics in thin film ferroelectric capacitors. Appl. Phys. Lett. 87, 082902 (2005).

    Article  Google Scholar 

  27. Yang, S. M. et al. Domain wall motion in epitaxial Pb(Zr,Ti)O3 capacitors investigated by modified piezoresponse force microscopy. Appl. Phys. Lett. 92, 252901 (2008).

    Article  Google Scholar 

  28. McGilly, L., Yudin, P., Feigl, L., Tagantsev, A. & Setter, N. Controlling domain wall motion in ferroelectric thin films. Nat. Nanotechnol. 10, 145–150 (2015).

    Article  CAS  Google Scholar 

  29. Alden, J. S. et al. Strain solitons and topological defects in bilayer graphene. Proc. Natl Acad. Sci. USA 110, 11256–11260 (2013).

    Article  CAS  Google Scholar 

  30. Cao, Y. et al. Superlattice-induced insulating states and valley-protected orbits in twisted bilayer graphene. Phys. Rev. Lett. 117, 116804 (2016).

    Article  CAS  Google Scholar 

  31. Kim, K. et al. Van der Waals heterostructures with high accuracy rotational alignment. Nano Lett. 16, 1989–1995 (2016).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We thank F. Spaepen, J. Mundy and D. Bennett for important discussions. K.K., A.Y., J.K., D.P., S.M.Y. and H.Y. acknowledge the support by the Samsung Research Funding & Incubation Center of Samsung Electronics under project number SRFC-MA2002-01. S.M.Y. and H.Y. acknowledge the support by the National Research Foundation of Korea grant funded by the Korean government (Ministry of Science and ICT; no. 2022R1A4A1033562). P.K. acknowledges the support from the Army Research Office’s Multidisciplinary University Initiative (MURI) programme (W911NF-21-2-0147). R.E. acknowledges the support from the National Science Foundation (DMR-1922172) for TEM analysis. K.W. and T.T. acknowledge the support from the Japan Society for the Promotion of Science KAKENHI (grant nos 19H05790, 20H00354 and 21H05233).

Author information

Author notes

  1. These authors contributed equally: Kahyun Ko, Ayoung Yuk, Rebecca Engelke.

Authors and Affiliations

  1. Department of Physics, Sogang University, Seoul, Republic of Korea

    Kahyun Ko, Ayoung Yuk, Junhyung Kim, Daesung Park, Sang Mo Yang & Hyobin Yoo

  2. Department of Physics, Harvard University, Cambridge, MA, USA

    Rebecca Engelke, Stephen Carr, Hoseok Heo, Hongkun Park, Efthimios Kaxiras & Philip Kim

  3. Department of Physics, Brown University, Providence, RI, USA

    Stephen Carr

  4. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA

    Hoseok Heo & Hongkun Park

  5. Korea Electronics Technolgy Institute, Seongnam, Republic of Korea

    Hyun-Mi Kim, Seul-Gi Kim & Hyeongkeun Kim

  6. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan

    Takashi Taniguchi

  7. Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan

    Kenji Watanabe

  8. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

    Efthimios Kaxiras & Philip Kim

  9. Institute of Emergent Materials, Sogang University, Seoul, Republic of Korea

    Hyobin Yoo

Authors
  1. Kahyun Ko
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Ayoung Yuk
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Rebecca Engelke
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Stephen Carr
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Junhyung Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Daesung Park
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Hoseok Heo
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Hyun-Mi Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Seul-Gi Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Hyeongkeun Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Takashi Taniguchi
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Kenji Watanabe
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Hongkun Park
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. Efthimios Kaxiras
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. Sang Mo Yang
    View author publications

    You can also search for this author in PubMed Google Scholar

  16. Philip Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

  17. Hyobin Yoo
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

H.Y., P.K. and S.M.Y. conceived the experiments. K.K., A.Y., J.K., D.P. and H.Y. fabricated the TEM devices. K.K., A.Y., R.E., J.K., H.-M.K., S.-G.K., H.K. and H.Y. performed the TEM experiments. K.K., A.Y., R.E., S.C., H.-M.K., E.K., S.M.Y., P.K. and H.Y. analysed the data. S.C. performed the theoretical analysis. H.H. and H.P. grew the bulk WSe2 crystals. K.W. and T.T. grew the bulk h-BN crystals. K.K., A.Y., R.E., S.C., S.M.Y., P.K. and H.Y. wrote the manuscript. All authors contributed to the overall scientific interpretation and edited the manuscript.

Corresponding authors

Correspondence to Sang Mo Yang, Philip Kim or Hyobin Yoo.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Materials thanks Moshe Ben Shalom and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Tunable polarizability of the twisted bilayer TMD by moiré length and domain anisotropy.

(a-c) TEM dark field (DF) images of twisted bilayer TMD plotted as a function of vertical electric field \({{\rm{\varepsilon }}}_{{\rm{z}}}\) for different moiré lengths. (d) The normalized domain area difference \(\widetilde{\triangle {\rm{A}}}\) plotted as a function of \({{\rm{\varepsilon }}}_{{\rm{z}}}\) for the three different moiré lengths shown in (a-c). The error bars are a result of the uncertainty in the thresholding operation on the dark and light pixels. (e) Schematics of moiré cell geometry under electric field. When the relative displacement between the top and bottom layer only includes the rotational component, the domain structure shows equilateral triangles (left). When the relative displacement includes the rotational as well as the uniaxial components, the domain structure shows distorted triangular shapes (right). (f) polarizability change with the moiré size and shape. We plot \(d\widetilde{\triangle {\rm{A}}/}d{{\rm{\varepsilon }}}_{{\rm{z}}}\) (red colour symbols, left axis) and \({x}_{s}^{-1}d\widetilde{\triangle {\rm{A}}/}d{{\rm{\varepsilon }}}_{{\rm{z}}}\,\)(blue colour symbols, right axis) obtained from moiré cells shown in Extended Data Fig. 1f as a function of the moiré length \(\lambda .\) Triangle marks represent moiré cells with angles within 30% of the equilateral shape (\({x}_{s}\cong 1\)). Square marks represent moiré cells that deviate further from the equilateral shape (\({x}_{s}\gg 1\)). Horizontal error bars represent the standard deviations of the sidelengths of each polygon. (g) Colour plot of \(d\widetilde{\triangle {\rm{A}}/}d{{\rm{\varepsilon }}}_{{\rm{z}}}\) as a function of \({{\rm{\varepsilon }}}_{{\rm{z}}}\) and xs. Green lines are the values of \(\widetilde{\triangle {\rm{A}}}\) plotted as a function of the vertical electric field \({{\rm{\varepsilon }}}_{{\rm{z}}}\) centered at the corresponding value of λxs. The errors in estimating \(\widetilde{\triangle {\rm{A}}}\) due to the uncertainty in the thresholding operation on the dark and light pixels are represented as the thicknesses of the green lines. (h) Simulated colour plot of \(d\widetilde{\triangle {\rm{A}}/}d{{\rm{\varepsilon }}}_{{\rm{z}}}\) and lines of \(\widetilde{\triangle {\rm{A}}}\) vs \({{\rm{\varepsilon }}}_{{\rm{z}}}\) at various values of λxs.

Extended Data Fig. 2 Removal of the nodes of the DWN at the sample edge.

Snapshots of TEM DF images plotted as a function of vertical electric fields during the gate sweep (See Video S6 for real-time observation).

Extended Data Fig. 3 Domain wall pinning at the sample edge.

(a-b) Snap shots of TEM DF images obtained during the electric field sweep. Yellow and red arrows indicate regions where the domain wall is pinned during the electric field sweep. Red and yellow dashed lines are drawn in the same position to show the change in domain wall. (c-d) ADF STEM images taken from the region where the domain wall pinning was confirmed by the snapshots of TEM DF images shown in a and b.

Extended Data Fig. 4 Domain wall pinning by the bubbles.

Snapshots of TEM DF images obtained during the electric field sweep. Coloured arrows indicate some of the pinning events by the bubbles (See Video S8 for real-time observation).

Extended Data Fig. 5 Domain wall pinning at the bulk pinning sites.

(a) Snapshots of TEM DF images obtained during the electric field sweep. The red arrow indicates a region where the domain wall pinning was observed. Magnified (b) ADF and (c) BF STEM images taken in the region where the domain wall pinning was confirmed in (a). The red arrow indicates the curved region in the domain wall caused by the pinning observed in (a). The green arrow indicates the domain wall that extends from the region indicated with the red arrow. The blue arrow indicates the linear feature where the WSe2 layer is locally strained. The insets show the lower magnification images with the magnified region indicated with the purple boxes. TEM DF images taken with Bragg peaks from WSe2 (d) and h-BN (e) layers. (f) SAED pattern obtained from the specimen that exhibits the Bragg peaks originating from WSe2, h-BN, and graphite layers.

Extended Data Fig. 6 Domain wall pinning at the bulk pinning sites.

(a) TEM DF image obtained from the region where the bulk pinning was confirmed. The red arrow indicates a region where the domain wall pinning was observed. (b) ADF STEM image obtained in the region indicated with the white dashed box in (a). (c) ADF and (d) BF STEM images taken simultaneously in the region marked with the white dashed box in (b).

Supplementary information

Supplementary Information

Supplementary Figs. 1–16, Methods and Notes.

Supplementary Video 1

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the region where the domain structural change was observed during the gate sweep.

Supplementary Video 2

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the region where the domain structural change was observed during the gate sweep.

Supplementary Video 3

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the MDAF region where a non-hysteretic linear response was observed during the gate sweep.

Supplementary Video 4

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the FE region where a hysteretic response was observed during the gate sweep.

Supplementary Video 5

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the FE region where a hysteretic response was observed during the gate sweep.

Supplementary Video 6

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the region where the node of the DWN was pushed out to the sample edge.

Supplementary Video 7

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the FE region where the domain wall pinning and depinning at the sample edge was observed.

Supplementary Video 8

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the FE region where the domain wall pinning and depinning by the bubbles was observed.

Supplementary Video 9

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the MDAF region where a non-hysteretic linear response was observed during the gate sweep.

Supplementary Video 10

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the MDAF region where a non-hysteretic linear response was observed during the gate sweep.

Supplementary Video 11

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the MDAF region where a hysteretic response was observed during the gate sweep.

Supplementary Video 12

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the FE region where a hysteretic response was observed during the gate sweep.

Supplementary Video 13

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the FE region where a hysteretic response was observed during the gate sweep.

Supplementary Video 14

DF TEM video (\({\mathrm{g}}=10\bar{1}0\)) taken from the FE region where a hysteretic response was observed during the gate sweep.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Ko, K., Yuk, A., Engelke, R. et al. Operando electron microscopy investigation of polar domain dynamics in twisted van der Waals homobilayers. Nat. Mater. 22, 992–998 (2023). https://doi.org/10.1038/s41563-023-01595-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41563-023-01595-0

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing