Unconventional quantum Hall effect and Berry’s phase of 2π in bilayer graphene
Kostya S. Novoselov,Edward McCann,Sergey V. Morozov,Vladimir I. Fal'ko,Mikhail I. Katsnelson,Uli Zeitler,Da Jiang,Fred Schedin,Andre K. Geim +8 more
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TLDR
In this paper, a third type of integer quantum Hall effect is reported in bilayer graphene, where charge carriers have a parabolic energy spectrum but are chiral and show Berry's phase 2π affecting their quantum dynamics.Abstract:
There are two known distinct types of the integer quantum Hall effect. One is the conventional quantum Hall effect, characteristic of two-dimensional semiconductor systems1,2, and the other is its relativistic counterpart observed in graphene, where charge carriers mimic Dirac fermions characterized by Berry’s phase π, which results in shifted positions of the Hall plateaus3,4,5,6,7,8,9. Here we report a third type of the integer quantum Hall effect. Charge carriers in bilayer graphene have a parabolic energy spectrum but are chiral and show Berry’s phase 2π affecting their quantum dynamics. The Landau quantization of these fermions results in plateaus in Hall conductivity at standard integer positions, but the last (zero-level) plateau is missing. The zero-level anomaly is accompanied by metallic conductivity in the limit of low concentrations and high magnetic fields, in stark contrast to the conventional, insulating behaviour in this regime. The revealed chiral fermions have no known analogues and present an intriguing case for quantum-mechanical studies.read more
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Band gap and broken chirality in single-layer and bilayer graphene
Anastasia Varlet,Ming-Hao Liu,Dominik Bischoff,Pauline Simonet,Takashi Taniguchi,Kenji Watanabe,Klaus Richter,Thomas Ihn,Klaus Ensslin +8 more
TL;DR: In this article, the authors investigated the role of the band gap in the evolution of the pseudospin in a dual-gated bilayer graphene device and showed that the chirality in the energy range close to the gap can be attributed to the breaking of the Chirality.
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Layer-by-Layer Decoupling of Twisted Graphene Sheets Epitaxially Grown on a Metal Substrate.
Sabina Simon,Elena Voloshina,Julia Tesch,Felix Förschner,Vivien Enenkel,Charlotte Herbig,Charlotte Herbig,Timo Knispel,Alexander Tries,Jörg Kröger,Yuriy Dedkov,Mikhail Fonin +11 more
TL;DR: Using scanning tunneling microscopy and Landau-level spectroscopy, it is shown that for a monolayer and bilayers with small-angle rotations, Landau levels are fully suppressed, indicating that the metal-graphene interaction is largely confined to the first graphene layer.
Journal ArticleDOI
Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO3/SrTiO3 Heterostructures
Giriraj Jnawali,Mengchen Huang,Jen-Feng Hsu,Hyungwoo Lee,Jung-Woo Lee,Patrick Irvin,Chang-Beom Eom,Brian D'Urso,Jeremy Levy +8 more
TL;DR: High mobility graphene field-effect devices, fabricated on the complex-oxide heterostructure LaAlO3 /SrTiO3 , exhibit quantum interference signatures up to room temperature and hold promise for the realization of new classical and quantum information technologies.
Journal ArticleDOI
Rich magneto-absorption spectra of AAB-stacked trilayer graphene
TL;DR: In this article, a generalized tight-binding model is developed to investigate the feature-rich magneto-optical properties of AAB-stacked trilayer graphene, and three intragroup and six intergroup inter-Landau-level (inter-LL) optical excitations largely enrich magneto absorption peaks.
Journal ArticleDOI
Traits and characteristics of interacting Dirac fermions in monolayer and bilayer graphene
TL;DR: In this paper, the effect of bias voltage and orientation of the magnetic field on the interaction strength of a bilayer system was investigated, and it was shown that the stability of the Pfaffian state can be greatly enhanced by applying an in-plane magnetic field.
References
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Electric Field Effect in Atomically Thin Carbon Films
Kostya S. Novoselov,Andre K. Geim,Sergey V. Morozov,Da Jiang,Y. Zhang,S. V. Dubonos,Irina V. Grigorieva,A. A. Firsov +7 more
TL;DR: Monocrystalline graphitic films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands and they exhibit a strong ambipolar electric field effect.
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Kostya S. Novoselov,A. K. Geim,Sergey V. Morozov,Da Jiang,Mikhail I. Katsnelson,Irina V. Grigorieva,S. V. Dubonos,A. A. Firsov +7 more
TL;DR: This study reports an experimental study of a condensed-matter system (graphene, a single atomic layer of carbon) in which electron transport is essentially governed by Dirac's (relativistic) equation and reveals a variety of unusual phenomena that are characteristic of two-dimensional Dirac fermions.
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Experimental observation of the quantum Hall effect and Berry's phase in graphene
TL;DR: In this paper, an experimental investigation of magneto-transport in a high-mobility single layer of Graphene is presented, where an unusual half-integer quantum Hall effect for both electron and hole carriers in graphene is observed.
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Two-dimensional atomic crystals
Kostya S. Novoselov,Da Jiang,Fred Schedin,Timothy J. Booth,V. V. Khotkevich,Sergey V. Morozov,Andre K. Geim +6 more
TL;DR: By using micromechanical cleavage, a variety of 2D crystals including single layers of boron nitride, graphite, several dichalcogenides, and complex oxides are prepared and studied.
Journal Article
Experimental Observation of Quantum Hall Effect and Berry's Phase in Graphene
TL;DR: An experimental investigation of magneto-transport in a high-mobility single layer of graphene observes an unusual half-integer quantum Hall effect for both electron and hole carriers in graphene.