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8 pages, 2186 KiB

Open AccessCommunication

Ferroelectric Polarization in an h-BN-Encapsulated 30°-Twisted Bilayer–Graphene Heterostructure

by Lingling Ren and Baojuan Dong

Magnetochemistry 2023, 9(5), 116; https://doi.org/10.3390/magnetochemistry9050116 - 26 Apr 2023

Cited by 2 | Viewed by 3375

Recently, the emergent two-dimensional (2D) ferroelectric materials have provided new possibilities for the miniaturization of ferroelectric systems and the integration of novel 2D nano-electronic devices. In addition to the intrinsic ferroelectrics exfoliated from bulk, 2D heterostructures hybridized from electrically non-polarized van der Waals (vdW) materials have also been proven to be a promising platform for the construction of ferroelectricity. Here, we report 30° twisted bilayer–graphene (TBLG) incommensurate moiré superlattice encapsulated by hexagonal boron nitride (h-BN), in which robust hysteretic resistance was detected at the top interface between h-BN and the TBLG from room temperature down to 40

mK

. The hysteretic phenomenon can be understood by the extra carrier induced by the interfacial 2D ferroelectric polarization, which is estimated to be around

0.7 pC / m

. Our work of interfacial ferroelectric heterostructure achieved by a TBLG/h-BN hybrid system expands the 2D ferroelectric families and opens more possibilities for future coupling the ferroelectricity with rich electronic and optical properties in vdW twistronic devices. Full article

(This article belongs to the Special Issue Advances in Magnetic Two Dimensional Materials)

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11 pages, 2346 KiB

Open AccessArticle

Diamane-like Films Based on Twisted G/BN Bilayers: DFT Modelling of Atomic Structures and Electronic Properties

by Victor A. Demin and Leonid A. Chernozatonskii

Nanomaterials 2023, 13(5), 841; https://doi.org/10.3390/nano13050841 - 24 Feb 2023

Cited by 6 | Viewed by 2047

Abstract

Diamanes are unique 2D carbon materials that can be obtained by the adsorption of light atoms or molecular groups onto the surfaces of bilayer graphene. Modification of the parent bilayers, such as through twisting of the layers and the substitution of one of the layers with BN, leads to drastic changes in the structure and properties of diamane-like materials. Here, we present the results of the DFT modelling of new stable diamane-like films based on twisted Moiré G/BN bilayers. The set of angles at which this structure becomes commensurate was found. We used two commensurate structures with twisted angles of θ = 10.9° and θ = 25.3° with the smallest period as the base for the formation of the diamane-like material. Previous theoretical investigations did not take into account the incommensurability of graphene and boron nitride monolayers when considering diamane-like films. The double-sided hydrogenation or fluorination of Moiré G/BN bilayers and the following interlayer covalent bonding led to the opening of a gap up to 3.1 eV, which was lower than the corresponding values of h-BN and c-BN. The considered G/BN diamane-like films offer great potential in the future for a variety of engineering applications. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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14 pages, 1472 KiB

Open AccessArticle

Moiré-like Superlattice Generated van Hove Singularities in a Strained CuO₂ Double Layer

by Artem O. Sboychakov, Kliment I. Kugel and Antonio Bianconi

Condens. Matter 2022, 7(3), 50; https://doi.org/10.3390/condmat7030050 - 23 Aug 2022

Cited by 3 | Viewed by 2310

Abstract

While it is known that the double-layer Bi

_{2}

_{2}

CaCu

_{2}

_{8 + y}

While it is known that the double-layer Bi

_{2}

_{2}

CaCu

_{2}

_{8 + y}

(BSCCO) cuprate superconductor exhibits a one-dimensional (1D) incommensurate superlattice (IS), the effect of IS on the electronic structure remains elusive. Following the recent shift of interest from an underdoped phase to optimum and overdoped phases in BSCCO by increasing the hole doping x, controlled by the oxygen interstitials concentration y, here we focus on the multiple splitting of the density of states (DOS) peaks and emergence of higher order van Hove singularities (VHS) due to the 1D incommensurate superlattice. It is known that the 1D incommensurate wave vector

q = ϵ b

(where

b

is the reciprocal lattice vector of the orthorhombic lattice) is controlled by the misfit strain between different atomic layers in the range

0.209

–

0.215

in BSCCO and in the range

0.209

–

0.25

in Bi

_{2}

_{2}

_{1 - x}

_{x}

_{2}

_{8 + y}

(BSCYCO). This work reports the theoretical calculation of a complex pattern of VHS due to the 1D incommensurate superlattice with large 1D quasi-commensurate supercells with the wave vector

ϵ = 9 / η

in the range

36 > η > 43

. The similarity of the complex VHS splitting and appearing of higher order VHS in a mismatched CuO

_{2}

bilayer with VHS due to the moiré lattice in strained twisted bilayer graphene is discussed. This makes a mismatched CuO

_{2}

bilayer quite promising for constructing quantum devices with tuned physical characteristics. Full article

(This article belongs to the Section Superconductivity)

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