Ultrahigh-resolution scanning microwave impedance microscopy of moiré lattices and superstructures

Kyunghoon Lee; M Iqbal Bakti Utama; Salman Kahn; Appalakondaiah Samudrala; Nicolas Leconte; Birui Yang; Shuopei Wang; Kenji Watanabe; Takashi Taniguchi; M Virginia P Altoé; Guangyu Zhang; Alexander Weber-Bargioni; Michael Crommie; Paul D Ashby; Jeil Jung; Feng Wang; Alex Zettl

doi:10.1126/sciadv.abd1919

Ultrahigh-resolution scanning microwave impedance microscopy of moiré lattices and superstructures

Sci Adv. 2020 Dec 9;6(50):eabd1919. doi: 10.1126/sciadv.abd1919. Print 2020 Dec.

Authors

Kyunghoon Lee^{1

2

3}, M Iqbal Bakti Utama^{1

2

4}, Salman Kahn^{1

2}, Appalakondaiah Samudrala⁵, Nicolas Leconte⁵, Birui Yang¹, Shuopei Wang^{6

7}, Kenji Watanabe⁸, Takashi Taniguchi⁹, M Virginia P Altoé¹⁰, Guangyu Zhang^{6

7}, Alexander Weber-Bargioni¹⁰, Michael Crommie^{1

2

3}, Paul D Ashby¹⁰, Jeil Jung⁵, Feng Wang^{11

2

3}, Alex Zettl^{11

2

3}

Affiliations

¹ Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA.
² Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
³ Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁴ Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA 94720, USA.
⁵ Department of Physics, University of Seoul, Seoul, South Korea.
⁶ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
⁷ Collaborative Innovation Center of Quantum Matter, Beijing, China.
⁸ Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁹ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
¹⁰ Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
¹¹ Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA. azettl@berkeley.edu fengwang76@berkeley.edu.

Abstract

Two-dimensional heterostructures composed of layers with slightly different lattice vectors exhibit new periodic structure known as moiré lattices, which, in turn, can support novel correlated and topological phenomena. Moreover, moiré superstructures can emerge from multiple misaligned moiré lattices or inhomogeneous strain distributions, offering additional degrees of freedom in tailoring electronic structure. High-resolution imaging of the moiré lattices and superstructures is critical for understanding the emerging physics. Here, we report the imaging of moiré lattices and superstructures in graphene-based samples under ambient conditions using an ultrahigh-resolution implementation of scanning microwave impedance microscopy. Although the probe tip has a gross radius of ~100 nm, spatial resolution better than 5 nm is achieved, which allows direct visualization of the structural details in moiré lattices and the composite super-moiré. We also demonstrate artificial synthesis of novel superstructures, including the Kagome moiré arising from the interplay between different layers.

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