Unraveling Strain Gradient Induced Electromechanical Coupling in Twisted Double Bilayer Graphene Moiré Superlattices

Li，Yuhao1,2; Wang，Xiao2,3; Tang，Deqi3; Wang，Xi1,4; Watanabe，Kenji5; Taniguchi，Takashi6; Gamelin，Daniel R.4; Cobden，David H.1; Yankowitz，Matthew1,7; Xu，Xiaodong1,7; Li，Jiangyu2,3,8

2021

10.1002/adma.202105879

ADVANCED MATERIALS   影响因子和分区

0935-9648

1521-4095

Moiré superlattices of 2D materials with a small twist angle are thought to exhibit appreciable flexoelectric effect, though unambiguous confirmation of their flexoelectricity is challenging due to artifacts associated with commonly used piezoresponse force microscopy (PFM). For example, unexpectedly small phase contrast (≈8°) between opposite flexoelectric polarizations is reported in twisted bilayer graphene (tBG), though theoretically predicted value is 180°. Here a methodology is developed to extract intrinsic moiré flexoelectricity using twisted double bilayer graphene (tDBG) as a model system, probed by lateral PFM. For small twist angle samples, it is found that a vectorial decomposition is essential to recover the small intrinsic flexoelectric response at domain walls from a large background signal. The obtained threefold symmetry of commensurate domains with significant flexoelectric response at domain walls is fully consistent with the theoretical calculations. Incommensurate domains in tDBG with relatively large twist angles can also be observed by this technique. A general strategy is provided here for unraveling intrinsic flexoelectricity in van der Waals moiré superlattices while providing insights into engineered symmetry breaking in centrosymmetric materials.

flexoelectricity lateral piezoelectric force microscope moiré superlattice twisted double bilayer graphene

SCI ; EI

英语

NI论文

通讯

WOS:000705118100001

20214111012081

Electromechanical coupling ; Graphene ; Scanning probe microscopy ; Van der Waals forces

Nanotechnology:761 ; Chemistry:801 ; Physical Chemistry:801.4 ; Chemical Products Generally:804 ; Atomic and Molecular Physics:931.3

MATERIALS SCIENCE

2-s2.0-85116744268

Scopus

1.Department of Physics,University of Washington,Seattle,98195,United States
2.Department of Materials Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
3.Shenzhen Key Laboratory of Nanobiomechanics,Shenzhen Institutes of Advanced Technology,Chinese Academy of Sciences,Shenzhen,518055,China
4.Department of Chemistry,University of Washington,Seattle,98195,United States
5.Research Center for Functional Materials,National Institute for Materials Science,Tsukuba,1-1 Namiki,305-0044,Japan
6.International Center for Materials Nanoarchitectonics,National Institute for Materials Science,Tsukuba,1-1 Namiki,305-0044,Japan
7.Department of Materials Science and Engineering,University of Washington,Seattle,98195,United States
8.Guangdong Provisional Key Laboratory of Functional Oxide Materials and Devices,Southern University of Science and Technology,Shenzhen,518055,China

Li，Yuhao,Wang，Xiao,Tang，Deqi,et al. Unraveling Strain Gradient Induced Electromechanical Coupling in Twisted Double Bilayer Graphene Moiré Superlattices[J]. ADVANCED MATERIALS,2021,33.

Li，Yuhao.,Wang，Xiao.,Tang，Deqi.,Wang，Xi.,Watanabe，Kenji.,...&Li，Jiangyu.(2021).Unraveling Strain Gradient Induced Electromechanical Coupling in Twisted Double Bilayer Graphene Moiré Superlattices.ADVANCED MATERIALS,33.

Li，Yuhao,et al."Unraveling Strain Gradient Induced Electromechanical Coupling in Twisted Double Bilayer Graphene Moiré Superlattices".ADVANCED MATERIALS 33(2021).