scholarly journals Quantifying the Charge Carrier Interaction in Metallic Twisted Bilayer Graphene Superlattices

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1306
Author(s):  
Evgueni F. Talantsev
Keyword(s):  
Charge Carrier ◽  
Bilayer Graphene ◽  
Electron Interaction ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Linear Temperature ◽  
Electron Phonon Interaction ◽  
Wide Range ◽  
Carrier Interaction ◽  
Twisted Bilayer Graphene

The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron–phonon interaction, while the others showed evidence for electron–electron or electron–magnon interactions. Here we propose to resolve this problem by generalizing the Bloch–Grüneisen equation and using it for the analysis of the temperature dependent resistivity in TBG. It is a well-established theoretical result that the Bloch–Grüneisen equation power-law exponent, p, exhibits exact integer values for certain mechanisms. For instance, p = 5 implies the electron–phonon interaction, p = 3 is associated with the electron–magnon interaction and p = 2 applies to the electron–electron interaction. Here we interpret the linear temperature-dependent resistance, widely observed in TBG, as p→1, which implies the quasielastic charge interaction with acoustic phonons. Thus, we fitted TBG resistance curves to the Bloch–Grüneisen equation, where we propose that p is a free-fitting parameter. We found that TBGs have a smoothly varied p-value (ranging from 1.4 to 4.4) depending on the Moiré superlattice constant, λ, or the charge carrier concentration, n. This implies that different mechanisms of the charge carrier interaction in TBG superlattices smoothly transition from one mechanism to another depending on, at least, λ and n. The proposed generalized Bloch–Grüneisen equation is applicable to a wide range of disciplines, including superconductivity and geology.

Raman spectra of twisted bilayer graphene close to the magic angle

2D Materials ◽  
2022 ◽  
Author(s):  
Tiago Campolina Barbosa ◽  
Andreij C. Gadelha ◽  
Douglas A. A. Ohlberg ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Laser Excitation ◽  
Bilayer Graphene ◽  
Geometrical Model ◽  
Excitation Wavelength ◽  
Magic Angle ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Excitation Laser ◽  
Twisted Bilayer Graphene

Abstract In this work, we study the Raman spectra of twisted bilayer graphene samples as a function of their twist-angles (θ), ranging from 0.03º to 3.40º, where local θ are determined by analysis of their associated moiré superlattices, as imaged by scanning microwave impedance microscopy. Three standard excitation laser lines are used (457, 532, and 633 nm wavelengths), and the main Raman active graphene bands (G and 2D) are considered. Our results reveal that electron-phonon interaction influences the G band's linewidth close to the magic angle regardless of laser excitation wavelength. Also, the 2D band lineshape in the θ < 1º regime is dictated by crystal lattice and depends on both the Bernal (AB and BA) stacking bilayer graphene and strain soliton regions (SP) [1]. We propose a geometrical model to explain the 2D lineshape variations, and from it, we estimate the SP width when moving towards the magic angle.

scholarly journals Temperature Dependence of G and D’ Phonons in Monolayer to Few-Layer Graphene with Vacancies

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Mingming Yang ◽  
Longlong Wang ◽  
Xiaofen Qiao ◽  
Yi Liu ◽  
Yufan Liu ◽  
...  
Keyword(s):  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Intrinsic Properties ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Layer Graphene ◽  
A Value ◽  
Few Layer Graphene

Abstract The defects into the hexagonal network of a sp2-hybridized carbon atom have been demonstrated to have a significant influence on intrinsic properties of graphene systems. In this paper, we presented a study of temperature-dependent Raman spectra of G peak and D’ band at low temperatures from 78 to 318 K in defective monolayer to few-layer graphene induced by ion C+ bombardment under the determination of vacancy uniformity. Defects lead to the increase of the negative temperature coefficient of G peak, with a value almost identical to that of D’ band. However, the variation of frequency and linewidth of G peak with layer number is contrary to D’ band. It derives from the related electron-phonon interaction in G and D’ phonon in the disorder-induced Raman scattering process. Our results are helpful to understand the mechanism of temperature-dependent phonons in graphene-based materials and provide valuable information on thermal properties of defects for the application of graphene-based devices.

Temperature-dependent dielectric loss in BaTiO3: Competition between tunnelling probability and electron-phonon interaction

2021 ◽  
Vol 257 ◽  
pp. 123792
Author(s):  
Aanchal Sati ◽  
Anil Kumar ◽  
Vikash Mishra ◽  
Kamal Warshi ◽  
Preeti Pokhriyal ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction

scholarly journals Electron-Phonon Interaction and Charge Carrier Mass Enhancement inSrTiO3

2008 ◽  
Vol 100 (22) ◽  
Author(s):  
J. L. M. van Mechelen ◽  
D. van der Marel ◽  
C. Grimaldi ◽  
A. B. Kuzmenko ◽  
N. P. Armitage ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Mass Enhancement

scholarly journals Bilayer graphene: physics and application outlook in photonics

Nanophotonics ◽  
2015 ◽  
Vol 4 (1) ◽  
pp. 115-127 ◽  
Author(s):  
Hugen Yan
Keyword(s):  
Layered Materials ◽  
Bilayer Graphene ◽  
Layered Material ◽  
Two Dimensional ◽  
Fano Resonances ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Basic Physics ◽  
Gap Opening ◽  
Plasmon Interaction

AbstractLayered materials, such as graphene, transition metal dichacogenides and black phosphorus have attracted lots of attention recently. They are emerging novel materials in electronics and photonics, with tremendous potential in revolutionizing the traditional electronics and photonics industry. Marrying layered material to the nanophotonics is being proved fruitful. With the recent emphasis and development of metasurfaces in nanophotonics, atomically thin materials can find their unique position and strength in this field. In this article, I will focus on one specific two dimensional material: bilayer graphene. Basic physics will be reviewed, such as band-gap opening, electron-phonon interaction, phonon-plasmon interaction and Fano resonances in the optical response. Moreover, I will review the application of bilayer graphene as a sensitive and fast photodetector. An outlook will be given in the final part of the paper.

scholarly journals Interaction effects and superconductivity signatures in twisted double-bilayer WSe2

2020 ◽  
Vol 5 (9) ◽  
pp. 1309-1316 ◽  
Author(s):  
Liheng An ◽  
Xiangbin Cai ◽  
Ding Pei ◽  
Meizhen Huang ◽  
Zefei Wu ◽  
...  
Keyword(s):  
Interaction Effects ◽  
Bilayer Graphene ◽  
Insulator Transition ◽  
Electron Interaction ◽  
Flat Band ◽  
Two Dimensional ◽  
Twisted Bilayer Graphene ◽  
Interaction Phenomena

Twisted bilayer graphene provides a new two-dimensional platform for studying electron interaction phenomena and flat band properties such as correlated insulator transition, superconductivity and ferromagnetism at certain magic angles.

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