Torsional Force Microscopy of Van der Waals Moirés and Atomic Lattices

ORAL

Abstract

Controlling exotic properties of moiré superlattices in twisted Van der Waals (VdW) materials requires identification of twist angle disorder and strain during their preparation. With individual moiré unit cells varying in size from a few nanometers to few thousand nanometers, techniques that are capable of directly visualizing moiré superlattices across all relevant length scales at experimentally convenient conditions remain scarce. In this work, we introduce AFM based Torsional Force Microscopy (TFM) to visualize moirés in air, at room temperature, on commercially available AFMs, without the need for any electrical contact to the sample or the AFM tip [1]. TFM involves operating the AFM in contact-mode while exciting a torsional resonance of the AFM cantilever; the torsional resonance is sensitive to the local dynamic friction and reproducibly images moirés formed at the graphene-hBN and graphene-graphene interfaces. We observe that subsurface moirés can also be revealed by increasing the vertical loading force on the AFM tip. Additionally, atomic lattices of graphene and hBN are also observed, enabling precise determination of crystallographic orientation of flakes.

[1] M. Pendharkar, et al., preprint arXiv:2308.08814 (2023)

* US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract DE-AC02- 76SF00515. SLAC National Accelerator Laboratory, Q-BALMS Laboratory Directed Research and Development. National Science Foundation ECCS-2026822. Gordon and Betty Moore Foundation GBMF9460. JSPS KAKENHI (Grant Numbers 21H05233 and 23H02052) and World Premier International Research Center Initiative (WPI), MEXT, Japan.

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Publication: 1. Preprint: Torsional Force Microscopy of Van der Waals Moirés and Atomic Lattices, M. Pendharkar, et al., arXiv:2308.08814 (2023)
2. Under review: Torsional Force Microscopy of Van der Waals Moirés and Atomic Lattices, M. Pendharkar, et al., Proceedings of the National Academy of Sciences (PNAS) (Submitted August 2023).

Presenters

  • Mihir Pendharkar

    Stanford University, Stanford Institute for Materials & Energy Sciences, Stanford University

Authors

  • Mihir Pendharkar

    Stanford University, Stanford Institute for Materials & Energy Sciences, Stanford University

  • Steven Tran

    Stanford University, Stanford Institute for Materials & Energy Sciences, Stanford University

  • Gregory Zaborski Jr.

    Stanford University

  • Joe Finney

    Stanford University

  • Aaron L Sharpe

    Stanford University, Sandia National Laboratories

  • Rupini Kamat

    Stanford Institute for Materials and Energy Sciences, Stanford University Physics Department, Stanford University

  • Sandesh S Kalantre

    Stanford Institute for Materials and Energy Sciences, Stanford University Physics Department, Stanford University

  • Marisa L Hocking

    Stanford University, Stanford Institute for Materials & Energy Sciences, Stanford University

  • Nathan J Bittner

    Independent Researcher, Independent

  • Kenji Watanabe

    National Institute for Materials Science, NIMS, Research Center for Electronic and Optical Materials, National Institute for Materials Science, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science

  • Takashi Taniguchi

    Kyoto Univ, National Institute for Materials Science, Research Center for Materials Nanoarchitectonics, Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, National Institute for Materials Sciences, NIMS, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, International Center for Materials Nanoarchitectonics, NIMS, Japan, International Center for Materials Nanoarchitectonics, Tsukuba, National Institue for Materials Science, Kyoto University, National Institute of Materials Science, International Center for Materials Nanoarchitectonics and National Institute for Materials Science

  • Bede Pittenger

    Bruker Nano Surfaces

  • Christina J Newcomb

    Stanford University

  • Marc Kastner

    Stanford University, Stanford Institute for Materials and Energy Sciences, Stanford University Physics Department, Massachusetts Institute of Technology Physics Department, Stanford Univ

  • Andrew J Mannix

    Stanford University

  • David Goldhaber-Gordon

    Stanford University, Stanford Institute for Materials and Energy Sciences, Stanford University Physics Department, Department of Physics, Stanford University, Stanford, California, Stanford Institute for Materials & Energy Sciences, Stanford University