Article
Materials Science, Multidisciplinary
A. L. Rakhmanov, A. V. Rozhkov, A. O. Sboychakov
Summary: This study analytically and numerically investigates the electronic properties of a circular quantum dot made from AA-stacked bilayer graphene. The researchers observe a set of discrete dot radii where the low-energy electron states are degenerate with respect to the layer parity. They find that by analogy with the "magic angles" in twisted bilayer graphene, these radii are referred to as "magic". The researchers argue that this analogy can be useful for the theoretical description of the electronic properties of twisted bilayer graphene.
Article
Materials Science, Multidisciplinary
V. Apinyan, T. K. Kopec
Summary: This paper investigates the antiferromagnetic and excitonic correlations in AA-stacked bilayer graphene, considering the impact of an external electric field potential and different particle-filling regimes. The study reveals that antiferromagnetism and excitonic phases can coexist away from half-filling, with the presence of a critical Coulomb interaction potential determining the transition between single-valued and triple-valued excitonic states.
Article
Multidisciplinary Sciences
Bin-Bin Chen, Yuan Da Liao, Ziyu Chen, Oskar Vafek, Jian Kang, Wei Li, Zi Yang Meng
Summary: This study investigates the correlated electron phenomena in magic-angle twisted bilayer graphene, proposing a Mott-Hubbard perspective and identifying a quantum phase transition in the lattice model. The results not only clarify the mechanism of the quantum anomalous Hall state, but also provide an example of the topological Mott insulator in the strong coupling limit.
NATURE COMMUNICATIONS
(2021)
Article
Multidisciplinary Sciences
Nikhil Tilak, Xinyuan Lai, Shuang Wu, Zhenyuan Zhang, Mingyu Xu, Raquel de Almeida Ribeiro, Paul C. Canfield, Eva Y. Andrei
Summary: Researchers have demonstrated that flat bands in twisted bilayer graphene can amplify small doping inhomogeneity, leading to carrier confinement, a phenomenon previously only achievable in the presence of a strong magnetic field. This suggests that improving sample quality is crucial for studying electron physics in graphene.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Condensed Matter
Yawar Mohammadi
Summary: The study of plasmon modes in doped AA-stacked bilayer graphene reveals the potential of using it as a tunable plasmonic device. The long-wavelength acoustic plasmon's existence is hindered as the chemical potential approaches the interlayer hopping energy. Optimal long-lived optical plasmon in undoped AA-stacked BLG can be achieved by satisfying specific conditions.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Physics, Condensed Matter
Z. Z. Alisultanov, G. O. Abdullaev
Summary: We investigate quantum oscillations in AA and AB graphene bilayers with broken intralayer P-symmetry under a gate voltage, considering both doped and undoped cases. The gate voltage induces an inverted band region in the bilayer's spectrum, resulting in additional peaks in density of states oscillations. We demonstrate the presence of oscillations in the dielectric phase when the chemical potential is pinned within the band gap. These effects are analyzed for different types of layer stacking in the bilayer. It is shown that graphene bilayers are better suited for studying anomalous oscillations compared to narrow-gap topological insulators. Furthermore, the results can be applied to other graphene-like bilayer materials such as transition metal dichalcogenide bilayers.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Physics, Multidisciplinary
Hector Sainz-Cruz, Pierre A. Pantaleon, Vo Tien Phong, Alejandro Jimeno-Pozo, Francisco Guinea
Summary: Junctions between scanning tunneling microscope (STM) tip and superconducting twisted bilayer graphene (TBG) as well as TBG Josephson junctions (JJs) provide valuable insights into the symmetry of the superconductors' order parameter. Comparison of even and odd valley exchange superconducting phases (s-wave or f-wave) reveals that the critical current in mixed (s and f) JJs is strongly affected by the junction-lattice angle. Andreev reflection in STM-TBG junctions leads to a prominent subgap conductance peak in the case of f-wave, as observed in experiments.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Jian Kang, B. Andrei Bernevig, Oskar Vafek
Summary: The research presents a framework for understanding the cascade transitions and Landau level degeneracies of twisted bilayer graphene, which sheds light on new insights. By varying the filling, different mass excitations can be generated, explaining the diversity of features observed.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Condensed Matter
Tomasz Chwiej
Summary: The large lattice constant of Moire superlattice in twisted bilayer graphene allows for the observation of Landau levels splitting into Hofstadter butterflies. The question of its robustness against spatial potential fluctuations is still being debated. By studying the energy structure of the twisted bilayer system under both homogeneous magnetic field and bias voltage, it is found that Landau levels are still formed despite the broken translational symmetry.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Materials Science, Multidisciplinary
O. Farkad, F. Elfatouaki, R. Takassa, S. Hassine, Y. Ijdiyaou, E. A. Ibnouelghazi, D. Abouelaoualim
Summary: In this study, the effects of strontium intercalation on the structure and electronic properties of AA-stacked bilayer graphene were investigated using first-principles calculations. The results showed that strontium intercalation influences the electronic band structures of graphene, with significant contributions from the p and d orbitals of the strontium atom. The electron density is highest around the carbon atoms, allowing for efficient transfer of electric charges from the strontium atom. The intercalated graphene material exhibited metallic behavior, as confirmed by the increase in static refractive index in the vertical polarization and divergence in the parallel mode.
MATERIALS TODAY COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
S. D. Eder, S. K. Hellner, S. Forti, J. M. Nordbotten, J. R. Manson, C. Coletti, B. Holst
Summary: Experimental measurements on AB-stacked bilayer graphene show that the bending rigidity increases with temperature, contrary to some theoretical predictions. The data is fitted to a linear dependence to obtain a specific equation for kappa(T), which provides insight when compared to existing predictions and room temperature measurements.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Yantao Li, Adam Eaton, H. A. Fertig, Babak Seradjeh
Summary: We have discovered a new type of magic-angle phenomena when an AA-stacked graphene bilayer is twisted relative to another graphene system with band touching. At certain angles, multiple anisotropic Dirac cones coexist in the twisted multilayer structures, which we refer to as Dirac magic. The twist angle and perpendicular electric field can be used to tune the topological Lifshitz transitions induced by the anisotropy of the Dirac cones.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Yang-Zhi Chou, Sankar Das Sarma
Summary: In this study, we systematically investigate emergent Kondo lattice models in magic-angle twisted bilayer graphene using the topological heavy fermion representation. We demonstrate a series of symmetric strongly correlated metallic states and possibly realize a topological Dirac Kondo semimetal. The findings suggest that magic-angle twisted bilayer graphene may serve as a solid-state quantum simulator for novel magnetic orders on a triangular lattice.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Condensed Matter
Shi-Chao Fang, Xiao-Jun Zheng, Hai-Qing Lin, Zhong-Bing Huang
Summary: The study demonstrates that in the half-filled Hubbard model on AA-stacked honeycomb lattice, a dominant chirald+idwave superconductivity can be induced by a perpendicular electric field. The effective pairing interaction of chirald+idsuperconductivity increases with increasing the on-site Coulomb interaction. The results strongly suggest that the AA-stacked graphene system is a good candidate for chirald+idsuperconductor.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Engineering, Electrical & Electronic
L. Azadi, S. Shojaei
Summary: The optical absorption and bandgap of bilayer graphene superlattice are affected by structural parameters, with enhanced absorption achieved by increasing the magnitude of the static periodic potential applied. Light polarization influences absorption, while different ratios of periodic region widths do not affect absorption.
JOURNAL OF COMPUTATIONAL ELECTRONICS
(2021)
