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We investigate the bandwidth compression due to out of plane pressure of the moire flatbands near charge neutrality in twisted bilayer graphene for a continuous range of small rotation angles of up to $\sim2.5^{\circ}$. The flatband…

Mesoscale and Nanoscale Physics · Physics 2019-01-29 Bheema Lingam Chittari , Nicolas Leconte , Srivani Javvaji , Jeil Jung

Twisted graphene bilayers provide a versatile platform to engineer metamaterials with novel emergent properties by exploiting the resulting geometric moir\'{e} superlattice. Such superlattices are known to host bulk valley currents at tiny…

Mesoscale and Nanoscale Physics · Physics 2019-09-04 T. M. R. Wolf , J. L. Lado , G. Blatter , O. Zilberberg

We develop a theory for the electron-phonon interaction effects on the electronic properties of graphene. We analytically calculate the electron self-energy, spectral function and band velocity renormalization due to phonon-mediated…

Materials Science · Physics 2009-11-13 Wang-Kong Tse , S. Das Sarma

Twisted bilayer graphene near the magic angle is known to have a cascade of insulating phases at integer filling factors of the low-energy bands. In this Letter we address the nature of these phases through an unrestricted, large-scale…

Strongly Correlated Electrons · Physics 2024-09-30 Khagendra Adhikari , Kangjun Seo , K. S. D. Beach , Bruno Uchoa

In twisted bilayer graphene (TBG) devices, local strains frequently coexist and intertwine with the twist-angle-dependent moir\'e superlattice, significantly influencing the electronic properties of TBG, yet their combined effects remain…

Near a magic twist angle, bilayer graphene transforms from a weakly correlated Fermi liquid to a strongly correlated two-dimensional electron system with properties that are extraordinarily sensitive to carrier density and to controllable…

Mesoscale and Nanoscale Physics · Physics 2020-12-14 Eva Y. Andrei , Allan H. MacDonald

The line shape of the double-resonant $2D$ Raman mode in bilayer graphene is often considered to be characteristic for a certain laser excitation energy. Here, in a joint experimental and theoretical study, we analyze the dependence of the…

Mesoscale and Nanoscale Physics · Physics 2018-12-19 Felix Herziger , Christoph Tyborski , Oliver Ochedowski , Marika Schleberger , Janina Maultzsch

We study the effect of an in-plane magnetic field on the non-interacting dispersion of twisted bilayer graphene. Our analysis is rooted in the chirally symmetric continuum model, whose zero-field band structure hosts exactly flat bands and…

Strongly Correlated Electrons · Physics 2020-05-20 Yves H. Kwan , S. A. Parameswaran , S. L. Sondhi

Electron-phonon coupling in graphene is extensively modeled and simulated from first principles. We find that using an accurate model for the polarizations of the acoustic phonon modes is crucial to obtain correct numerical results. The…

When twisted to angles near 1{\deg}, graphene multilayers provide a new window on electron correlation physics by hosting gate-tuneable strongly-correlated states, including insulators, superconductors, and unusual magnets. Here we report…

We use temperature-dependent resistivity in small-angle twisted double bilayer graphene to measure bandwidths and gaps of the bands. This electron-hole asymmetric system has one set of non-dispersing bands that splits into two flat bands…

Magic angle twisted bilayer graphene has emerged as a powerful platform for studying strongly correlated electron physics, owing to its almost dispersionless low-energy bands and the ability to tune the band filling by electrostatic gating.…

Mesoscale and Nanoscale Physics · Physics 2021-07-21 Nikhil Tilak , Xinyuan Lai , Shuang Wu , Zhenyuan Zhang , Mingyu Xu , Raquel de Almeida Ribeiro , Paul C Canfield , Eva Y. Andrei

We have investigated the effect of twisting on electronic band structure, effective mass and carrier mobilities of three prototypes of AGNRs (N=6, 7 & 8) using Density functional theory combined with Deformation potential theory and…

Mesoscale and Nanoscale Physics · Physics 2020-07-15 Rajesh Thakur , P. K. Ahluwalia , Ashok Kumar , Brij Mohan , Raman Sharma

Twisted bilayer graphene (TBG) represents a highly tunable, strongly correlated electron system owed to its unique flat electronic bands. However, understanding the single-particle band structure alone has been challenging due to complex…

We present symmetry properties of the lattice vibrations of graphene nanoribbons with pure armchair (AGNR) and zigzag edges (ZGNR). In non-symmorphic nanoribbons the phonon modes at the edge of the Brillouin zone are twofold degenerate,…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 Roland Gillen , Marcel Mohr , Janina Maultzsch

Recent experimental and theoretical investigations demonstrate that twisted trilayer graphene (tTLG) is a highly tunable platform to study the correlated insulating states, ferromagnetism, and superconducting properties. Here we explore the…

Mesoscale and Nanoscale Physics · Physics 2021-11-17 Zewen Wu , Xueheng Kuang , Zhen Zhan , Shengjun Yuan

The spectrum of electron-phonon complexes in a monolayer graphene is investigated in the presence of a perpendicular quantizing magnetic field. Despite the small electron-phonon coupling, usual perturbation theory is inapplicable for…

Mesoscale and Nanoscale Physics · Physics 2013-01-21 J. Zhu , S. M. Badalyan , F. Peeters

Despite the structures and properties of tilt grain boundaries of graphite surface and graphene have been extensively studied, their effect on the structures and electronic spectra of graphene layers has not been fully addressed. Here we…

Mesoscale and Nanoscale Physics · Physics 2014-05-13 Long-Jing Yin , Jia-Bin Qiao , Wen-Xiao Wang , Zhao-Dong Chu , Kai Fen Zhang , Rui-Fen Dou , Chun Lei Gao , Jin-Feng Jia , Jia-Cai Nie , Lin He

This study theoretically investigates the contact conductance in twisted bilayer graphene (TBG), providing a theoretical explanation for recent experimental observations from scanning tunneling microscopy (STM) and conductive atomic force…

Mesoscale and Nanoscale Physics · Physics 2025-06-30 Kevin J. U. Vidarte , Caio Lewenkopf , F. Crasto de Lima , R. Hiroki Miwa , Felipe Pérez Riffo , Eric Suárez Morell

We derive a material-realistic real-space many-body Hamiltonian for twisted bilayer graphene from first principles, including both single-particle hopping terms for $p_z$ electrons and long-range Coulomb interactions. By disentangling low-…

Mesoscale and Nanoscale Physics · Physics 2022-01-24 Tom Westerhout , Mikhail I. Katsnelson , Malte Rösner