Article
Physics, Multidisciplinary
Ya-Ning Ren, Mo-Han Zhang, Chao Yan, Yu Zhang, Lin He
Summary: This study focuses on magneto-oscillations in 2D electron systems and their application in different stacked graphene layers. It demonstrates that STM can locally measure these oscillations, providing a convenient and effective method for studying such materials.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2021)
Article
Nanoscience & Nanotechnology
Wen-Wu Xie, Yong-Mei Zhang, Zhi Ping Niu
Summary: The presence of interlayer potential, Rashba spin-orbit coupling, and exchange field leads to a topological phase transition in bilayer graphene. The sharp peaks of longitudinal conductivity at low frequency contribute more to energy radiation. Energy and angular momentum radiation can be used to distinguish different topological phases.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2023)
Article
Materials Science, Multidisciplinary
Haozhe Wang, Zhenpeng Yao, Gang Seob Jung, Qichen Song, Marek Hempel, Tomas Palacios, Gang Chen, Markus J. Buehler, Alan Aspuru-Guzik, Jing Kong
Summary: Bilayer graphene, with its fascinating electrical behavior, is often limited by the presence of thicker graphene islands, but the layer-by-layer growth mode with tuned interface adhesive energy can suppress multilayer impurities and result in mechanically robust bilayer graphene with AB stacking or small twisting angles.
Article
Materials Science, Multidisciplinary
Xiu-Cai Jiang, Yi-Yuan Zhao, Yu-Zhong Zhang
Summary: The article presents a way to tune the tiny gap in twisted bilayer graphene into a large gap. Through comprehensive understanding of the physical origin of gap opening, the study reveals that effective interlayer hopping and charge imbalance are key factors in creating a gap. Based on tight-binding calculations, the researchers suggest using periodic transverse inhomogeneous pressure to tune the interlayer hoppings and create a gap of over 100 meV. First-principles calculations further confirm the feasibility of this approach.
Article
Physics, Multidisciplinary
J. A. Briones-Torres, R. Perez-Alvarez, S. Molina-Valdovinos, I Rodriguez-Vargas
Summary: This study investigates the thermoelectric response of gated bilayer graphene superlattices (GBGSLs) for the first time. The Seebeck coefficient, power factor, figure of merit, output power and efficiency are analyzed for different temperatures and superlattice structural parameters. The impact of minibands, minigaps, and intrinsic resonances in bilayer graphene structures is also examined. The interplay between minibands and Fano resonances is analyzed as a potential mechanism for improving the thermoelectric response of GBGSLs. The density of states is computed to determine the involvement of electron state redistribution-accumulation in the thermoelectric response of GBGSLs.
Article
Multidisciplinary Sciences
M. V. O. Moutinho, G. S. N. Eliel, A. Righi, R. N. Gontijo, M. Paillet, T. Michel, Po-Wen Chiu, P. Venezuela, M. A. Pimenta
Summary: Twisted bilayer graphene is an intriguing system for tuning electronic and optical properties by controlling the twisting angle between layers. Raman spectroscopy is a fundamental tool in studying TBG, revealing distinct enhancement of different phonons through intralayer and interlayer processes. Experimental results are nicely explained by theoretical calculations of double-resonance Raman intensity in graphene, showing the impact of quantum interference and symmetry requirements on the resonant Raman response.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Sun-Woo Kim, Sunam Jeon, Moon Jip Park, Youngkuk Kim
Summary: The energy spectrum of twisted bilayer graphene (TBG) exhibits recursive higher-order topological properties known as higher-order topological insulator (HOTI) phases. These HOTI phases, characterized by localized corner states, are replicas of the original HOTIs and maintain the self-similarity of the Hofstadter spectrum. It is shown that TBG exhibits exact flux translational symmetry at all commensurate angles, and the original HOTI phase re-emerges at a half-flux periodicity, preserving the effective twofold rotation. Multiple replicas of the original HOTIs are also found for fluxes without protecting symmetries, featuring localized corner states and edge-localized real-space topological markers. These replica HOTIs result from different interaction scales in TBG, including intralayer and interlayer couplings. The topological aspect of the Hofstadter butterflies observed in this study highlights the symmetry-protected topology in quantum fractals.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Yong-Qiang Liu, Zhongru Ren, Hongcheng Yin, Jinhai Sun, Liangsheng Li
Summary: This paper presents the dispersion theory and modal characteristics of graphene metasurfaces featuring surface plasmon polaritons (SPPs). The obtained dispersion expressions show the splitting of SPPs into two new modes on the double-layer graphene metasurface. The study investigates the dispersion relation and propagating properties as a function of key physical parameters, indicating great potential for constructing various novel plasmonic devices in the Terahertz band.
Article
Materials Science, Multidisciplinary
Weidong Yan, Langquan Shui, Wengen Ouyang, Ze Liu
Summary: In this study, a thermodynamic model for twisted bilayer graphene is derived within the framework of classical statistical mechanics. The configuration entropy of twisted bilayer graphene relative to AB-stacked bilayer graphene is shown to be proportional to the logarithmic function of the ratio of Moire period and lattice constant. Furthermore, a possible dissipation mechanism in the interlayer sliding of twisted bilayer graphene is discussed based on observations of out-of-plane deformation following Moire patterns.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Materials Science, Multidisciplinary
Nicolas Leconte, Srivani Javvaji, Jiaqi An, Appalakondaiah Samudrala, Jeil Jung
Summary: We propose a multiscale density functional theory and tight-binding approach to study the atomic and electronic structures of twisted bilayer graphene. By calibrating the interlayer tunneling, we determine the flat band magic angle to be 1.08 degrees. The interatomic force fields are constructed using various input from stacking and interlayer distance-dependent density functional theory calculations. By combining different parameters, our model yields high-resolution spectral functions that are consistent with experimental angle-resolved photoemission spectroscopy. Our analysis reveals the interdependence between atomic and electronic structures, and suggests that the determined magic angle can be obtained without further rescaling of the interlayer tunneling.
Article
Materials Science, Multidisciplinary
Wen Jiang, Chang Liu, Xiaonan Ma, Xing Yu, Shunbo Hu, Xi Li, Lee A. Burton, Yu Liu, Yangyang Chen, Pan Guo, Xiangyang Kong, Laurent Bellaiche, Wei Ren
Summary: This study uses first-principles computations to reveal the origin and unique properties of the ferroelectricity in bilayer h-BN.
Article
Chemistry, Physical
Nathanael P. Kazmierczak, Madeline Van Winkle, Colin Ophus, Karen C. Bustillo, Stephen Carr, Hamish G. Brown, Jim Ciston, Takashi Taniguchi, Kenji Watanabe, D. Kwabena Bediako
Summary: Twisted bilayer graphene exhibits two-regime reconstruction mechanics based on twist angle, with applied heterostrain accumulating anisotropically in saddle-point regions to generate distinctive striped strain phases. Nanoscale spatial fluctuations in twist angle and uniaxial heterostrain were statistically evaluated, revealing the prevalence of short-range disorder in moire heterostructures. This study provides insights into the twist-angle-dependent electronic behavior and structural relaxation, disorder, and strain in moire materials.
Article
Chemistry, Physical
Johannes Halle, Nicolas Neel, Joerg Kroeger
Summary: The research reveals that graphene phonons can be excited by the local injection of electrons and holes from the tip of a scanning tunneling microscope. Both monolayer and bilayer graphene exhibit distinct phonon signatures in spectroscopy, with differences in phonon energies and the presence of a Dirac cone plasmon excitation in bilayer graphene.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Editorial Material
Nanoscience & Nanotechnology
Tatiana Latychevskaia
Summary: The topological parameters of the channel network in twisted bilayer graphene can be manipulated by intercalating lithium atoms.
NATURE NANOTECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Robin Smeyers, Milorad V. V. Milosevic, Lucian Covaci
Summary: When using hexagonal boron-nitride (hBN) as a substrate for graphene, the resulting moire pattern creates secondary Dirac points. By encapsulating a multilayer graphene within aligned hBN sheets, the controlled moire stacking may offer even richer benefits. Tight-binding simulations on atomistically-relaxed heterostructures show that the gap at the secondary Dirac point can be opened in selected moire-stacking configurations, while gating can broadly tune the gap at the principal Dirac point and compress the first moire mini-band in width against the moire-induced gap at the secondary Dirac point. This mechanism can lead to flat bands under moderate gating, providing a convenient pathway towards electronically-controlled strongly-correlated states on demand in hBN-encapsulated bilayer graphene.
