Realizing one-dimensional moiré chains with strong electron localization in two-dimensional twisted bilayer WSe2
Edited by J.C. Davis, University of Oxford, Oxford, United Kingdom; received March 19, 2024; accepted October 3, 2024
Significance
Our study expands the field of two-dimensional (2D) correlated moiré physics to one-dimensional (1D) systems. Using scanning tunneling microscopy (STM), we create 1D moiré chains in twisted bilayer WSe2 with selectively filled electronic states. By applying a back-gate voltage and STM bias voltage, we manipulate the strong localized charge states of correlated electrons, paving the way for new correlated electronic states in 1D moiré systems.
Abstract
Two-dimensional (2D) moiré systems based on twisted bilayer graphene and transition metal dichalcogenides provide a promising platform to investigate emergent phenomena driven by strong electron–electron interactions in partially filled flat bands. A natural question arises: Is it possible to expand the 2D correlated moiré physics to one-dimensional (1D) that electron–electron correlation is expected to be further enhanced? This requires selectively doping of 1D moiré chain, which seems to be not within the grasp of today’s technology. Therefore, an experimental demonstration of the 1D moiré chain with partially filled electronic states remains absent. Here, we show that we can introduce 1D boundaries, separating two regions with different twist angles, in twisted bilayer WSe2 (tWSe2) by using scanning tunneling microscopy (STM) and demonstrate that the electronic states of 1D moiré sites along the boundaries can be selectively filled. The strong localized charge states of correlated moiré electrons in the 1D moiré chain can be directly imaged and manipulated by combining a back-gate voltage with the STM bias voltage. Our results open the door for realizing new correlated electronic states of the 1D moiré chain in 2D systems.
Get full access to this article
Purchase, subscribe or recommend this article to your librarian.
Data, Materials, and Software Availability
All study data are included in the article and/or supporting information.
Acknowledgments
This work was supported by the National Key R and D Program of China (Grant Nos. 2021YFA1401900, 2021YFA1400100), National Natural Science Foundation of China (Grant Nos. 12141401, 12425405, and 12404198), “the Fundamental Research Funds for the Central Universities” (Grant No. 310400209521), the China National Postdoctoral Program for Innovative Talents (Grant No. BX20240040), and the China Postdoctoral Science Foundation (2023M740296). The devices were fabricated using the transfer platform from Shanghai Onway Technology Co., Ltd.
Author contributions
Y.-N.R. and L.H. designed research; Y.-N.R. performed research; K.W. and T.T. contributed high-quality hBN substrates; Y.-N.R., H.-Y.R., and L.H. analyzed data; and Y.-N.R. and L.H. wrote the paper.
Competing interests
The authors declare no competing interest.
Supporting Information
Appendix 01 (PDF)
- Download
- 2.58 MB
Movie S1.
Dynamic schematic illustration of the influences on the charging effect at the moiré site as the tip is moved away from the moiré site at different bias voltages. At a bias voltage of Vb1 (left panel), the tip is positioned at the center of the moiré site, allowing the moiré band (MB) to cross the Fermi level, resulting in a charging effect. At a bias voltage of Vb2 (right panel), the band bending increases, so the tip must be at a distance r1 from the moiré site for the MB to cross the Fermi level, leading to a charging effect and creating a charging ring with a radius of r1.
- Download
- 4.75 MB
Movie S2.
A movie showing the evolution of moiré charging rings with changing bias voltage Vb, corresponding to Fig. 3a in the main text.
- Download
- 81.62 MB
Movie S3.
A movie showing the evolution of moiré charging rings with changing bias voltage Vb, corresponding to Fig. 3c in the main text.
- Download
- 50.28 MB
Movie S4.
A movie showing the evolution of moiré charging rings with changing bias voltage Vb at a back-gate voltage (Vg) of 15 V, corresponding to Figs. 4c and 4e in the main text.
- Download
- 64.97 MB
References
1
Y. Tang et al., Simulation of Hubbard model physics in WSe2/WS2 moiré superlattices. Nature 579, 353–358 (2020).
2
E. C. Regan et al., Mott and generalized Wigner crystal states in WSe2/WS2 moiré superlattices. Nature 579, 359–363 (2020).
3
L. Wang et al., Correlated electronic phases in twisted bilayer transition metal dichalcogenides. Nat. Mater. 19, 861–866 (2020).
4
Y. Xu et al., A tunable bilayer Hubbard model in twisted WSe2. Nat. Nanotech. 17, 934–939 (2022).
5
K. L. Seyler et al., Signatures of moiré-trapped valley excitons in MoSe2/WSe2 heterobilayers. Nature 567, 66–70 (2019).
6
K. Tran et al., Evidence for moiré excitons in van der Waals heterostructures. Nature 567, 71–75 (2019).
7
C. Jin et al., Observation of moiré excitons in WSe2/WS2 heterostructure superlattices. Nature 567, 76–80 (2019).
8
E. Liu et al., Signatures of moiré trions in WSe2/MoSe2 heterobilayers. Nature 594, 46–50 (2021).
9
L. Balents, C. R. Dean, D. K. Efetov, A. F. Young, Superconductivity and strong correlations in moiré flat bands. Nat. Phys. 16, 725–733 (2020).
10
E. Y. Andrei, A. H. MacDonald, Graphene bilayers with a twist. Nat. Mater. 19, 1265–1275 (2020).
11
Y.-N. Ren, Y. Zhang, Y.-W. Liu, L. He, Twistronics in graphene-based van der Waals structures. Chin. Phys. B 29, 117303 (2020).
12
Z. Zhang et al., Flat bands in twisted bilayer transition metal dichalcogenides. Nat. Phys. 16, 1093–1096 (2020).
13
H. Li et al., Imaging moiré flat bands in three-dimensional reconstructed WSe2/WS2 superlattices. Nat. Mater. 20, 945–950 (2021).
14
E. Li et al., Lattice reconstruction induced multiple ultra-flat bands in twisted bilayer Wse2. Nat. Commun. 12, 5601 (2021).
15
F. Wu, T. Lovorn, E. Tutuc, A. H. MacDonald, Hubbard model physics in transition metal dichalcogenide moiré bands. Phys. Rev. Lett. 121, 026402 (2018).
16
H. Li et al., Imaging local discharge cascades for correlated electrons in WS2/Wse2 moiré superlattices. Nat. Phys. 17, 1114–1119 (2021).
17
H. Li et al., Imaging two-dimensional generalized Wigner crystals. Nature 597, 650–654 (2021).
18
D. Pei et al., Observation of Γ-Valley moiré bands and emergent hexagonal lattice in twisted transition metal dichalcogenides. Phys. Rev. X 12, 021065 (2022).
19
P. W. Anderson, Resonating valence bonds: A new kind of insulator? Mater. Res. Bull. 8, 153–160 (1973).
20
B. J. Kim et al., Distinct spinon and holon dispersions in photoemission spectral functions from one-dimensional SrCuO2. Nat. Phys. 2, 397–401 (2006).
21
B. Lake, D. A. Tennant, C. D. Frost, S. E. Nagler, Quantum criticality and universal scaling of a quantum antiferromagnet. Nat. Mater. 4, 329–334 (2005).
22
C. Broholm et al., Quantum spin liquids. Science 367, eaay0668 (2020).
23
T. Zhu et al., Imaging gate-tunable Tomonaga-Luttinger liquids in 1H-MoSe2 mirror twin boundaries. Nat. Mater. 21, 748–753 (2022).
24
W. Jolie et al., Tomonaga-Luttinger liquid in a box: Electrons confined within MoS2 mirror-twin boundaries. Phys. Rev. X 9, 011055 (2019).
25
L. Wang et al., Direct observation of one-dimensional Peierls-type charge density wave in twin boundaries of monolayer MoTe2. ACS Nano 14, 8299–8306 (2020).
26
Q. Zheng et al., Tunable sample-wide electronic Kagome lattice in low-angle twisted bilayer graphene. Phys. Rev. Lett. 129, 076803 (2022).
27
C.-Y. Hao et al., Creating a custom-designed moiré magnifying glass to probe local atomic lattice rotations in twisted bilayer graphene. Phys. Rev. B 108, 125429 (2023).
28
H.-Y. Ren et al., Electron-electron interaction and correlation-induced two density waves with different Fermi velocities in graphene quantum dots. Phys. Rev. B 108, L081408 (2023).
29
Q. Zheng et al., Molecular collapse states in graphene/WSe2 heterostructure quantum dots. Phys. Rev. Lett. 130, 076202 (2023).
30
Q. Zheng, Y. Zhuang, Q.-F. Sun, L. He, Coexistence of electron whispering gallery modes and atomic collapse states in graphene/WSe2 heterostructure quantum dots. Nat. Commun. 13, 1597 (2022).
31
H. Yoo et al., Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene. Nat. Mater. 18, 448–453 (2019).
32
N. P. Kazmierczak et al., Strain fields in twisted bilayer graphene. Nat. Mater. 20, 956–963 (2021).
33
Y.-N. Ren et al., Real-space mapping of local sub-degree lattice rotations in twisted bilayer graphene magnified by moiré superlattices. Nano Lett. 23, 1836 (2023).
34
N. A. Pradhan, N. Liu, C. Silien, W. Ho, Atomic scale conductance induced by single impurity charging. Phys. Rev. Lett. 94, 076801 (2005).
35
K. Teichmann et al., Controlled charge switching on a single donor with a scanning tunneling microscope. Phys. Rev. Lett. 101, 076103 (2008).
36
V. W. Brar et al., Gate-controlled ionization and screening of cobalt adatoms on a graphene surface. Nat. Phys. 7, 43–47 (2011).
37
D. Wong et al., Characterization and manipulation of individual defects in insulating hexagonal boron nitride using scanning tunnelling microscopy. Nat. Nanotechnol. 10, 949 (2015).
38
Y. Zhao et al., Creating and probing electron whispering-gallery modes in graphene. Science 348, 672–675 (2015).
39
Y.-N. Ren et al., Spatial and magnetic confinement of massless Dirac fermions. Phys. Rev. B 104, L161408 (2021).
40
Y.-N. Ren, Q. Cheng, Q.-F. Sun, L. He, Realizing valley-polarized energy spectra in bilayer graphene quantum dots via continuously tunable Berry phases. Phys. Rev. Lett. 128, 206805 (2022).
41
S.-Y. Li, Y. Su, Y.-N. Ren, L. He, Valley polarization and inversion in strained graphene via pseudo-Landau levels, valley splitting of real Landau levels, and confined states. Phys. Rev. Lett. 124, 106802 (2020).
42
N. M. Freitag et al., Electrostatically confined monolayer graphene quantum dots with orbital and valley splittings. Nano Lett. 16, 5798–5805 (2016).
43
N. M. Freitag et al., Large tunable valley splitting in edge-free graphene quantum dots on boron nitride. Nat. Nanotech. 13, 392–397 (2018).
Information & Authors
Information
Published in
Classifications
Copyright
Copyright © 2024 the Author(s). Published by PNAS. This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).
Data, Materials, and Software Availability
All study data are included in the article and/or supporting information.
Submission history
Received: March 19, 2024
Accepted: October 3, 2024
Published online: October 30, 2024
Published in issue: November 5, 2024
Keywords
Acknowledgments
This work was supported by the National Key R and D Program of China (Grant Nos. 2021YFA1401900, 2021YFA1400100), National Natural Science Foundation of China (Grant Nos. 12141401, 12425405, and 12404198), “the Fundamental Research Funds for the Central Universities” (Grant No. 310400209521), the China National Postdoctoral Program for Innovative Talents (Grant No. BX20240040), and the China Postdoctoral Science Foundation (2023M740296). The devices were fabricated using the transfer platform from Shanghai Onway Technology Co., Ltd.
Author contributions
Y.-N.R. and L.H. designed research; Y.-N.R. performed research; K.W. and T.T. contributed high-quality hBN substrates; Y.-N.R., H.-Y.R., and L.H. analyzed data; and Y.-N.R. and L.H. wrote the paper.
Competing interests
The authors declare no competing interest.
Notes
This article is a PNAS Direct Submission.
Authors
Metrics & Citations
Metrics
Altmetrics
Citations
Cite this article
Realizing one-dimensional moiré chains with strong electron localization in two-dimensional twisted bilayer WSe2, Proc. Natl. Acad. Sci. U.S.A.
121 (45) e2405582121,
https://doi.org/10.1073/pnas.2405582121
(2024).
Copied!
Copying failed.
Export the article citation data by selecting a format from the list below and clicking Export.
View Options
Login options
Check if you have access through your login credentials or your institution to get full access on this article.
Personal login Institutional LoginRecommend to a librarian
Recommend PNAS to a LibrarianPurchase options
Purchase this article to access the full text.
Restore content access
View options
PDF format
Download this article as a PDF file
DOWNLOAD PDF