Unconventional ferroelectricity in moiré heterostructures

Zheng, Ziqiong; Ma, Qiong; Bi, Zhen; Barrera, Sergio C. de la; Liu, Ming‐Hao; Mao, Nannan; Zhang, Yang; Kiper, Natasha; Watanabe, Kenji; Taniguchi, Takashi; Kong, Jing; Tisdale, William A.; Ashoori, R. C.; Gedik, Nuh; Fu, Liang; Xu, Su-Yang; Jarillo‐Herrero, Pablo

doi:10.1038/s41586-020-2970-9

Cited by 205 publications

(211 citation statements)

References 57 publications

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“…A wide-band insulator with strong polar covalent bonding between boron and nitrogen, hBN has proven itself indispensable for making high-quality vdW heterostructures 13,14 and lateral superlattices, especially in combination with graphene 12,[15][16][17][18][19][20] . Very recently, ferroelectric-like charge polarization has been observed on bilayer-graphene/hBN superlattices 21 . However, the possibility of generating a spontaneous charge polarization with the moiré superlattice of two twisted hBN crystals (twisted-hBN/hBN)-without graphenehas not been explored experimentally yet.…”

mentioning

confidence: 99%

Charge-polarized interfacial superlattices in marginally twisted hexagonal boron nitride

et al. 2021

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When two-dimensional crystals are brought into close proximity, their interaction results in reconstruction of electronic spectrum and crystal structure. Such reconstruction strongly depends on the twist angle between the crystals, which has received growing attention due to interesting electronic and optical properties that arise in graphene and transitional metal dichalcogenides. Here we study two insulating crystals of hexagonal boron nitride stacked at small twist angle. Using electrostatic force microscopy, we observe ferroelectric-like domains arranged in triangular superlattices with a large surface potential. The observation is attributed to interfacial elastic deformations that result in out-of-plane dipoles formed by pairs of boron and nitrogen atoms belonging to opposite interfacial surfaces. This creates a bilayer-thick ferroelectric with oppositely polarized (BN and NB) dipoles in neighbouring domains, in agreement with our modeling. These findings open up possibilities for designing van der Waals heterostructures and offer an alternative probe to study moiré-superlattice electrostatic potentials.

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confidence: 99%

Charge-polarized interfacial superlattices in marginally twisted hexagonal boron nitride

et al. 2021

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“…Reduced magnetism in Fe, Co, Ni [6,7] and in cuprates [19] and the unconventional ferroelectricity in moiré heterostructures [20] can be explained using the new flexible s electron role with non zero angular momentum. Michael addition reaction in chemistry is explained recently, after 130 years, by Hamlin et al [8].…”

Section: Exotic Propertiesmentioning

confidence: 99%

“…This is called the quantum revolution 1.0 and we are in the beginning of quantum revolution 2.0. Currently many new materials exhibit exotic properties like, unconventional superconductivity [1,2], room temperature superconductivity [3][4][5], reduced magnetism [6,7], reduced Pauli repulsion [8], giant negative thermal expansion [9] and unconventional ferroelectricity [10]. These exotic properties could not be explained completely with the existing quantum mechanical theory which is mysterious yet incredibly accurate.…”

Section: Introductionmentioning

confidence: 99%

Probing the Private Quantum Life of s Electrons in Atoms of Nanomaterials -A New Quantum Theoretical Insight

Iyakutti¹,

Vj²

2021

Preprint

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The exotic properties exhibited by some of the nanomaterials could not be explained by the existing quantum theory. As a result one is forced to look back at the development of the quantum theory and some of the inelegancies. First, the quantized orbital angular momentum of s electron in an atom is taken as zero. This may be an acceptable fact for s electrons in an individual atom, but for the s electrons in a crystal or nanomaterial, this is far from the real situation. Secondly, in the wave function Ψ(r,θ), θ is considered as a dimensionless variable. These inelegancies lead to the impression that the present quantum theory is a steppingstone to a more complete description of nature. Here arises a necessity for probing the private quantum life of s electrons in crystal or nanomaterial. By assigning dimension to θ on par with r, we have quantum engineered the orbital angular momentum and hence the orbital degrees of freedom of s electrons and their signatures in a crystal. This restoration leads to new non-zero angular quantum numbers to s electrons of atoms in a crystal/nanomaterial. As a result the s electron occupation in nanomaterial is altered. Its new physics implications in material science, quantum chemistry and quantum technology are highlighted in this paper.

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“…Normally, the 2D heterostructures are normally created by exfoliation and mechanical restacking process. [ 34–36 ] Just like the case in Lego blocks, the heterostructures are formed by step‐by‐step stacking. In the process, the multi‐step usually takes a long time and lacks controllability over location and orientation.…”

Section: Introductionmentioning

confidence: 99%

The More, the Better–Recent Advances in Construction of 2D Multi‐Heterostructures

Ruijie

et al. 2021

Adv Funct Materials

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The past few years have witnessed significant development in the controlled growth of 2D heterostructures. Among those kinds of heterostructures, vertical and lateral ones have drawn the most attention. Vertical heterostructures can be created in the mode of layer by layer. The layer number and sequence in the vertical orientation can be modulated and thus leading to customized properties. However, the fabrication of lateral heterostructures has been met with challenges. The most concerning issue is related to the consistency at the atomic scale when two layers are stitched in a lateral direction. Adhering to the concept of epitaxial growth, chemical vapor deposition (CVD) has exerted significant impact in forming 2D lateral heterostructures. In this review, recent academic breakthroughs involving controlled growth of multi‐heterostructures by CVD are present. The CVD technique in terms of growth parameters, choice of catalysts, and mechanism is fully emphasized, offering guidelines for shaping novel 2D heterostructures. Several novel multi‐heterostructures attained by the CVD method are exhibited. Further, the properties and devices are described to demonstrate the unique features of multi‐heterostructures. The great advances in precisely constructing multi‐heterostructure are expected to push forward the way for 2D materials to industrialization and commercialization.

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Unconventional ferroelectricity in moiré heterostructures

Cited by 205 publications

References 57 publications

Charge-polarized interfacial superlattices in marginally twisted hexagonal boron nitride

Charge-polarized interfacial superlattices in marginally twisted hexagonal boron nitride

Probing the Private Quantum Life of s Electrons in Atoms of Nanomaterials -A New Quantum Theoretical Insight

The More, the Better–Recent Advances in Construction of 2D Multi‐Heterostructures

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