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Related papers: Phonons in Twisted Bilayer Graphene

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We develop a low-energy continuum model for phonons in twisted moir\'e bilayers, based on a configuration-space approach. In this approach, interatomic force constants are obtained from density functional theory (DFT) calculations of…

Mesoscale and Nanoscale Physics · Physics 2023-05-12 Jonathan Z. Lu , Ziyan Zhu , Mattia Angeli , Daniel T. Larson , Efthimios Kaxiras

In twisted bilayer graphene, long-wavelength lattice fluctuations on the scale of the moir\'e period are dominated by phason modes, i.e., acoustic branches of the incommensurate lattice resulting from coherent superpositions of optical…

Mesoscale and Nanoscale Physics · Physics 2019-10-30 Héctor Ochoa

The electronic properties of twisted bilayer graphene on SiC substrate were studied via combination of transport measurements and scanning tunneling microscopy. We report the observation of enhanced intervalley scattering from one Dirac…

Mesoscale and Nanoscale Physics · Physics 2012-09-17 Lan Meng , Zhao-Dong Chu , Yanfeng Zhang , Ji-Yong Yang , Rui-Fen Dou , Jia-Cai Nie , Lin He

Graphene, as an atomic-thick ultrasoft membrane, almost has no resistance against out-of-plane deformations and, therefore, it is always wrinkled to a certain degree. Recently, corrugated structures and their effects on the electronic…

Mesoscale and Nanoscale Physics · Physics 2016-09-13 Si-Yu Li , Hua Jiang , Jiao-Jiao Zhou , Haiwen Liu , Fan Zhang , Lin He

We present the full in-plane phonon dispersion of graphite obtained from inelastic x-ray scattering, including the optical and acoustic branches, as well as the mid-frequency range between the $K$ and $M$ points in the Brillouin zone, where…

Materials Science · Physics 2009-11-13 M. Mohr , J. Maultzsch , E. Dobardzic , S. Reich , I. Milosevic , M. Damnjanovic , A. Bosak , M. Krisch , C. Thomsen

Spontaneous symmetry-breaking, where the ground state of a system has lower symmetry than the underlying Hamiltonian, is ubiquitous in physics. It leads to multiply-degenerate ground states, each with a different "broken" symmetry labeled…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 Jonathan S. Alden , Adam W. Tsen , Pinshane Y. Huang , Robert Hovden , Lola Brown , Jiwoong Park , David A. Muller , Paul L. McEuen

Twisted stacked few layer black phosphorus heterostructures were successfully fabricated in this work. Abnormal blue shifts in their Ag1 and Ag2 Raman peaks and unique optical reflections were observed in these samples. The phonon behavior…

Materials Science · Physics 2018-05-04 Tao Fang , Teren Liu , Zenan Jiang , Rui Yang , Peyman Servati , Guangrui , Xia

A Raman study of a back gated bilayer graphene sample is presented. The changes in the Fermi level induced by charge transfer splits the Raman G-band, hardening its higher component and softening the lower one. These two components are…

Mesoscale and Nanoscale Physics · Physics 2008-12-16 L. M. Malard , D. C. Elias , E. S. Alves , M. A. Pimenta

We study the atomic structure of twisted bilayer graphene, with very small mismatch angles ($\theta \sim 0.28^0$), a topic of intense recent interest. We use simulations, in which we combine a recently presented semi-empirical potential for…

Materials Science · Physics 2016-11-15 Sandeep K. Jain , Vladimir Juricic , Gerard T. Barkema

Recent measurements in several different laboratories report the observation of an approximately linear-in-temperature resistivity with a large twist-angle-dependent slope (or temperature coefficient) in moir\'e twisted bilayer graphene…

Mesoscale and Nanoscale Physics · Physics 2022-07-21 Sankar Das Sarma , Fengcheng Wu

Graphene, a one-layer honeycomb lattice of carbon atoms, exhibits unconventional phenomena and attracts much interest since its discovery. Recently, an unexpected Mott-like insulator state induced by moir\'e pattern and a superconducting…

Mesoscale and Nanoscale Physics · Physics 2019-11-22 Yao Wang , Yi-Jun Chang , Jun Gao , Yong-Heng Lu , Zhi-Qiang Jiao , Fang-Wei Ye , Xian-Min Jin

Using electrical transport experiments and shot noise thermometry, we investigate electron-phonon heat transfer rate in a suspended bilayer graphene. Contrary to monolayer graphene with heat flow via three-body supercollision scattering, we…

Mesoscale and Nanoscale Physics · Physics 2014-09-23 Antti Laitinen , Manohar Kumar , Mika Oksanen , Bernard Plaçais , Pauli Virtanen , Pertti Hakonen

Twisted bilayer graphene exhibits isolated, relatively flat electronic bands near charge neutrality when the interlayer rotation is tuned to specific magic angles. These small misalignments, typically below 1.1{\deg}, result in long-period…

Mesoscale and Nanoscale Physics · Physics 2026-03-26 Antonio Palamara , Michele Pisarra , Antonello Sindona

We present a theory of phonon-mediated superconductivity in near magic angle twisted bilayer graphene. Using a microscopic model for phonon coupling to moir\'e band electrons, we find that phonons generate attractive interactions in both…

Superconductivity · Physics 2018-12-19 Fengcheng Wu , A. H. MacDonald , Ivar Martin

In this work we study the behavior of the optical phonon modes in bilayer graphene devices by applying top gate voltage, using Raman scattering. We observe the splitting of the Raman G band as we tune the Fermi level of the sample, which is…

Mesoscale and Nanoscale Physics · Physics 2012-06-07 D. L. Mafra , P. Gava , L. M. Malard , R. S. Borges , G. G. Silva , J. A. Leon , F. Plentz , F. Mauri , M. A. Pimenta

The surprising insulating and superconducting states of narrow-band graphene twisted bilayers have been mostly discussed so far in terms of strong electron correlation, with little or no attention to phonons and electron-phonon effects. We…

Strongly Correlated Electrons · Physics 2019-10-16 M. Angeli , E. Tosatti , M. Fabrizio

We present a first-principles study of the electron-phonon (e-ph) interactions and their contributions to the linewidths for the optical phonon modes at $\Gamma$ and K in one to three-layer graphene. It is found that due to the interlayer…

Materials Science · Physics 2009-03-31 Jia-An Yan , W. Y. Ruan , M. Y. Chou

Twisted bilayer graphene (tBLG) provides us with a large rotational freedom to explore new physics and novel device applications, but many of its basic properties remain unresolved. Here we report the synthesis and systematic Raman study of…

Though graphene has been intensively studied by Raman spectroscopy, in this letter, we report a study of second-order overtone and combinational Raman modes in an unexplored range of 1690-2150 cm-1 in nonsuspended commensurate (AB-stacked),…

Materials Science · Physics 2010-10-19 Chunxiao Cong , Ting Yu , Riichiro Saito

We investigate the electronic density redistribution of rotated bilayer graphene under a perpendicular electric field, showing that the layers are actually coupled even for large angles. This layer-layer coupling is evidenced by the charge…

Mesoscale and Nanoscale Physics · Physics 2012-03-26 E. Suárez Morell , P. Vargas , L. Chico , L. Brey