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We report on infrared spectroscopy of bilayer graphene integrated in gated structures. We observed a significant asymmetry in the optical conductivity upon electrostatic doping of electrons and holes. We show that this finding arises from a…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Z. Q. Li , E. A. Henriksen , Z. Jiang , Z. Hao , M. C. Martin , P. Kim , H. L. Stormer , D. N. Basov

We present a compelling evidence for the opening of a bandgap in exfoliated bottom-gated bilayer graphene by fitting the gate-voltage modulated infrared reflectivity spectra in a large range of doping levels with a tight-binding model and…

Strongly Correlated Electrons · Physics 2015-05-13 A. B. Kuzmenko , I. Crassee , D. van der Marel , P. Blake , K. S. Novoselov

It has been predicted that application of a strong electric field perpendicular to the plane of bilayer graphene can induce a significant band gap. We have measured the optical conductivity of bilayer graphene with an efficient electrolyte…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Kin Fai Mak , Chun Hung Lui , Jie Shan , Tony F. Heinz

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…

The electronic structure and optical response of electrically gated bilayer graphene are studied by first-principles approaches. We have obtained the induced band gap that is in good agreement with experiment when the applied electric field…

Mesoscale and Nanoscale Physics · Physics 2015-03-13 Li Yang

The electronic properties of doped bilayer graphene in presence of bottom and top gates have been studied and characterized by means of Density Functional Theory calculations. Varying independently the bottom and top gates it is possible to…

Materials Science · Physics 2015-05-13 Paola Gava , Michele Lazzeri , A. Marco Saitta , Francesco Mauri

We investigate the contribution of the low-energy electronic excitations towards the Raman spectrum of bilayer graphene for the incoming photon energy Omega >> 1eV. Starting with the four-band tight-binding model, we derive an effective…

Mesoscale and Nanoscale Physics · Physics 2010-08-17 M. Mucha-Kruczynski , O. Kashuba , V. I. Fal'ko

We review the electronic properties of bilayer graphene, beginning with a description of the tight-binding model of bilayer graphene and the derivation of the effective Hamiltonian describing massive chiral quasiparticles in two parabolic…

Mesoscale and Nanoscale Physics · Physics 2013-04-23 Edward McCann , Mikito Koshino

We report the infrared transmission measurement on electrically gated twisted bilayer graphene. The optical absorption spectrum clearly manifests the dramatic changes such as the splitting of inter-linear-band absorption step, the shift of…

Materials Science · Physics 2019-11-11 Kwangnam Yu , Van Luan Nguyen , Tae Soo Kim , Jiwon Jeon , Jiho Kim , Pilkyung Moon , Young Hee Lee , E. J. Choi

The tight-binding model of bilayer graphene is used to find the gap between the conduction and valence bands, as a function of both the gate voltage and as the doping by donors or acceptors. The total Hartree energy is minimized and the…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 L. A. Falkovsky

We discuss the physics of the tunable bandgap in bilayer graphene with the gate voltage and doping. A comparison with experimental data obtained by Kuzmenko et al [Phys. Rev. B \textbf{80}, 165406 (2009)] demonstrates the good agreement.

Mesoscale and Nanoscale Physics · Physics 2010-11-29 L. A. Falkovsky

Using infrared spectroscopy, we investigate bottom gated ABA-stacked trilayer graphene subject to an additional environment-induced p-type doping. We find that the Slonczewski-Weiss-McClure tight-binding model and the Kubo formula reproduce…

Mesoscale and Nanoscale Physics · Physics 2012-12-27 N. Ubrig , P. Blake , D. van der Marel , A. B. Kuzmenko

The tight-binding model of a graphene bilayer is used to find the gap between the conduction and valence bands, as a function of both the gate voltage and as the doping by donors or acceptors. The total Hartree energy is minimized and the…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 L. A. Falkovsky

We analyze the spectroscopic features of bilayer graphene determined by the formation of pairs of low-energy and split bands in this material. We show that the inter-Landau-level absorption spectrum in bilayer graphene at high magnetic…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 D. S. L. Abergel , Vladimir I. Fal'ko

Controlling the electronic structure of two-dimensional materials using the combination of twist angle and electrostatic doping is an effective means to induce emergent phenomena. In bilayer graphene with an interlayer twist angle near the…

The conductance, the transmission and the reflection probabilities through rectangular potential barriers and pn-junctions are obtained for bilayer graphene taking into account the four bands of the energy spectrum. We have evaluated the…

Mesoscale and Nanoscale Physics · Physics 2013-05-28 B. Van Duppen , F. M. Peeters

We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system -- \emph{biased bilayer}. The effect of the perpendicular…

The Raman shift, broadening, and relative Raman intensities of bilayer graphene are computed as functions of the electron concentration. We include dynamic effects for the phonon frequencies and we consider the gap induced in the band…

Materials Science · Physics 2009-09-11 Paola Gava , Michele Lazzeri , A. Marco Saitta , Francesco Mauri

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 calculate the finite-frequency conductivity of bilayer graphene with a relative twist between the layers. The low frequency response at zero doping shows a flat conductivity with value twice that of the monolayer case and at higher…

Mesoscale and Nanoscale Physics · Physics 2013-03-12 Calvin J. Tabert , Elisabeth J. Nicol
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